1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>The DB wrapper class — PyGreSQL 5.0 documentation</title>
<link rel="stylesheet" href="../../_static/cloud.css" type="text/css" />
<link rel="stylesheet" href="../../_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="../../_static/pygresql.css" type="text/css" />
<link rel="stylesheet" href="//fonts.googleapis.com/css?family=Noticia+Text|Open+Sans|Droid+Sans+Mono" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../../',
VERSION: '5.0.3',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="../../_static/jquery.js"></script>
<script type="text/javascript" src="../../_static/underscore.js"></script>
<script type="text/javascript" src="../../_static/doctools.js"></script>
<script type="text/javascript" src="../../_static/jquery.cookie.js"></script>
<script type="text/javascript" src="../../_static/cloud.js"></script>
<link rel="shortcut icon" href="../../_static/favicon.ico"/>
<link rel="copyright" title="Copyright" href="../../copyright.html" />
<link rel="top" title="PyGreSQL 5.0 documentation" href="../index.html" />
<link rel="up" title="pg — The Classic PyGreSQL Interface" href="index.html" />
<link rel="next" title="Query methods" href="query.html" />
<link rel="prev" title="Connection – The connection object" href="connection.html" />
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body role="document">
<div class="pageheader related" role="navigation" aria-label="related navigation">
<ul>
<li><a href="../../index.html">Home</a></li>
<li><a href="../../download/index.html">Download</a></li>
<li><a href="../index.html">Documentation</a></li>
<li><a href="../../community/index.html">Community</a></li>
</ul>
<div class="logo">
<a href="../../index.html">PyGreSQL</a>
</div>
</div>
</div>
<div class="relbar-top">
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="../../py-modindex.html" title="Python Module Index"
>modules</a> </li>
<li class="right" >
<a href="query.html" title="Query methods"
accesskey="N">next</a> </li>
<li class="right" >
<a href="connection.html" title="Connection – The connection object"
accesskey="P">previous</a> </li>
<li><a href="../index.html">PyGreSQL 5.0 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="index.html" accesskey="U"><code class="docutils literal"><span class="pre">pg</span></code> — The Classic PyGreSQL Interface</a> »</li>
</ul>
</div>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<div class="section" id="the-db-wrapper-class">
<h1>The DB wrapper class<a class="headerlink" href="#the-db-wrapper-class" title="Permalink to this headline">¶</a></h1>
<dl class="class">
<dt id="pg.DB">
<em class="property">class </em><code class="descclassname">pg.</code><code class="descname">DB</code><a class="headerlink" href="#pg.DB" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<p>The <a class="reference internal" href="connection.html#pg.Connection" title="pg.Connection"><code class="xref py py-class docutils literal"><span class="pre">Connection</span></code></a> methods are wrapped in the class <a class="reference internal" href="#pg.DB" title="pg.DB"><code class="xref py py-class docutils literal"><span class="pre">DB</span></code></a>
which also adds convenient higher level methods for working with the
database. It also serves as a context manager for the connection.
The preferred way to use this module is as follows:</p>
<div class="highlight-default"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">pg</span>
<span class="k">with</span> <span class="n">pg</span><span class="o">.</span><span class="n">DB</span><span class="p">(</span><span class="o">...</span><span class="p">)</span> <span class="k">as</span> <span class="n">db</span><span class="p">:</span> <span class="c"># for parameters, see below</span>
<span class="k">for</span> <span class="n">r</span> <span class="ow">in</span> <span class="n">db</span><span class="o">.</span><span class="n">query</span><span class="p">(</span> <span class="c"># just for example</span>
<span class="s">"SELECT foo, bar FROM foo_bar_table WHERE foo !~ bar"</span>
<span class="p">)</span><span class="o">.</span><span class="n">dictresult</span><span class="p">():</span>
<span class="nb">print</span><span class="p">(</span><span class="s">'%(foo)s %(bar)s'</span> <span class="o">%</span> <span class="n">r</span><span class="p">)</span>
</pre></div>
</div>
<p>This class can be subclassed as in this example:</p>
<div class="highlight-default"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">pg</span>
<span class="k">class</span> <span class="nc">DB_ride</span><span class="p">(</span><span class="n">pg</span><span class="o">.</span><span class="n">DB</span><span class="p">):</span>
<span class="sd">"""Ride database wrapper</span>
<span class="sd"> This class encapsulates the database functions and the specific</span>
<span class="sd"> methods for the ride database."""</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="sd">"""Open a database connection to the rides database"""</span>
<span class="n">pg</span><span class="o">.</span><span class="n">DB</span><span class="o">.</span><span class="n">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">dbname</span><span class="o">=</span><span class="s">'ride'</span><span class="p">)</span>
<span class="bp">self</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="s">"SET DATESTYLE TO 'ISO'"</span><span class="p">)</span>
<span class="p">[</span><span class="n">Add</span> <span class="ow">or</span> <span class="n">override</span> <span class="n">methods</span> <span class="n">here</span><span class="p">]</span>
</pre></div>
</div>
<p>The following describes the methods and variables of this class.</p>
<div class="section" id="initialization">
<h2>Initialization<a class="headerlink" href="#initialization" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="#pg.DB" title="pg.DB"><code class="xref py py-class docutils literal"><span class="pre">DB</span></code></a> class is initialized with the same arguments as the
<a class="reference internal" href="module.html#pg.connect" title="pg.connect"><code class="xref py py-func docutils literal"><span class="pre">connect()</span></code></a> function described above. It also initializes a few
internal variables. The statement <code class="docutils literal"><span class="pre">db</span> <span class="pre">=</span> <span class="pre">DB()</span></code> will open the local
database with the name of the user just like <code class="docutils literal"><span class="pre">connect()</span></code> does.</p>
<p>You can also initialize the DB class with an existing <a class="reference internal" href="index.html#module-pg" title="pg"><code class="xref py py-mod docutils literal"><span class="pre">pg</span></code></a> or <a class="reference internal" href="../pgdb/index.html#module-pgdb" title="pgdb"><code class="xref py py-mod docutils literal"><span class="pre">pgdb</span></code></a>
connection. Pass this connection as a single unnamed parameter, or as a
single parameter named <code class="docutils literal"><span class="pre">db</span></code>. This allows you to use all of the methods
of the DB class with a DB-API 2 compliant connection. Note that the
<a class="reference internal" href="connection.html#pg.Connection.close" title="pg.Connection.close"><code class="xref py py-meth docutils literal"><span class="pre">Connection.close()</span></code></a> and <code class="xref py py-meth docutils literal"><span class="pre">Connection.reopen()</span></code> methods are inoperative
in this case.</p>
</div>
<div class="section" id="pkey-return-the-primary-key-of-a-table">
<h2>pkey – return the primary key of a table<a class="headerlink" href="#pkey-return-the-primary-key-of-a-table" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.pkey">
<code class="descclassname">DB.</code><code class="descname">pkey</code><span class="sig-paren">(</span><em>table</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.pkey" title="Permalink to this definition">¶</a></dt>
<dd><p>Return the primary key of a table</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>table</strong> (<em>str</em>) – name of table</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">Name of the field which is the primary key of the table</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><strong>KeyError</strong> – the table does not have a primary key</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method returns the primary key of a table. Single primary keys are
returned as strings unless you set the composite flag. Composite primary
keys are always represented as tuples. Note that this raises a KeyError
if the table does not have a primary key.</p>
</div>
<div class="section" id="get-databases-get-list-of-databases-in-the-system">
<h2>get_databases – get list of databases in the system<a class="headerlink" href="#get-databases-get-list-of-databases-in-the-system" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_databases">
<code class="descclassname">DB.</code><code class="descname">get_databases</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_databases" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the list of databases in the system</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Returns:</th><td class="field-body">all databases in the system</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body">list</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Although you can do this with a simple select, it is added here for
convenience.</p>
</div>
<div class="section" id="get-relations-get-list-of-relations-in-connected-database">
<h2>get_relations – get list of relations in connected database<a class="headerlink" href="#get-relations-get-list-of-relations-in-connected-database" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_relations">
<code class="descclassname">DB.</code><code class="descname">get_relations</code><span class="sig-paren">(</span><span class="optional">[</span><em>kinds</em><span class="optional">]</span><span class="optional">[</span>, <em>system</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_relations" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the list of relations in connected database</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>kinds</strong> (<em>str</em>) – a string or sequence of type letters</li>
<li><strong>system</strong> (<em>bool</em>) – whether system relations should be returned</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">all relations of the given kinds in the database</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">list</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method returns the list of relations in the connected database. Although
you can do this with a simple select, it is added here for convenience. You
can select which kinds of relations you are interested in by passing type
letters in the <cite>kinds</cite> parameter. The type letters are <code class="docutils literal"><span class="pre">r</span></code> = ordinary table,
<code class="docutils literal"><span class="pre">i</span></code> = index, <code class="docutils literal"><span class="pre">S</span></code> = sequence, <code class="docutils literal"><span class="pre">v</span></code> = view, <code class="docutils literal"><span class="pre">c</span></code> = composite type,
<code class="docutils literal"><span class="pre">s</span></code> = special, <code class="docutils literal"><span class="pre">t</span></code> = TOAST table. If <cite>kinds</cite> is None or an empty string,
all relations are returned (this is also the default). If <cite>system</cite> is set to
<cite>True</cite>, then system tables and views (temporary tables, toast tables, catalog
vies and tables) will be returned as well, otherwise they will be ignored.</p>
</div>
<div class="section" id="get-tables-get-list-of-tables-in-connected-database">
<h2>get_tables – get list of tables in connected database<a class="headerlink" href="#get-tables-get-list-of-tables-in-connected-database" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_tables">
<code class="descclassname">DB.</code><code class="descname">get_tables</code><span class="sig-paren">(</span><span class="optional">[</span><em>system</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_tables" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the list of tables in connected database</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>system</strong> (<em>bool</em>) – whether system tables should be returned</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">all tables in connected database</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">list</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This is a shortcut for <code class="docutils literal"><span class="pre">get_relations('r',</span> <span class="pre">system)</span></code> that has been added for
convenience.</p>
</div>
<div class="section" id="get-attnames-get-the-attribute-names-of-a-table">
<h2>get_attnames – get the attribute names of a table<a class="headerlink" href="#get-attnames-get-the-attribute-names-of-a-table" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_attnames">
<code class="descclassname">DB.</code><code class="descname">get_attnames</code><span class="sig-paren">(</span><em>table</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_attnames" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the attribute names of a table</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>table</strong> (<em>str</em>) – name of table</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">an ordered dictionary mapping attribute names to type names</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Given the name of a table, digs out the set of attribute names.</p>
<p>Returns a read-only dictionary of attribute names (the names are the keys,
the values are the names of the attributes’ types) with the column names
in the proper order if you iterate over it.</p>
<p>By default, only a limited number of simple types will be returned.
You can get the regular types after enabling this by calling the
<a class="reference internal" href="#pg.DB.use_regtypes" title="pg.DB.use_regtypes"><code class="xref py py-meth docutils literal"><span class="pre">DB.use_regtypes()</span></code></a> method.</p>
</div>
<div class="section" id="has-table-privilege-check-table-privilege">
<h2>has_table_privilege – check table privilege<a class="headerlink" href="#has-table-privilege-check-table-privilege" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.has_table_privilege">
<code class="descclassname">DB.</code><code class="descname">has_table_privilege</code><span class="sig-paren">(</span><em>table</em>, <em>privilege</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.has_table_privilege" title="Permalink to this definition">¶</a></dt>
<dd><p>Check whether current user has specified table privilege</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – the name of the table</li>
<li><strong>privilege</strong> (<em>str</em>) – privilege to be checked – default is ‘select’</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">whether current user has specified table privilege</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">bool</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Returns True if the current user has the specified privilege for the table.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.0.</span></p>
</div>
</div>
<div class="section" id="get-set-parameter-get-or-set-run-time-parameters">
<h2>get/set_parameter – get or set run-time parameters<a class="headerlink" href="#get-set-parameter-get-or-set-run-time-parameters" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_parameter">
<code class="descclassname">DB.</code><code class="descname">get_parameter</code><span class="sig-paren">(</span><em>parameter</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_parameter" title="Permalink to this definition">¶</a></dt>
<dd><p>Get the value of run-time parameters</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><p class="first"><strong>parameter</strong> – the run-time parameter(s) to get</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the current value(s) of the run-time parameter(s)</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">str, list or dict</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>TypeError</strong> – Invalid parameter type(s)</li>
<li><strong>pg.ProgrammingError</strong> – Invalid parameter name(s)</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>If the parameter is a string, the return value will also be a string
that is the current setting of the run-time parameter with that name.</p>
<p>You can get several parameters at once by passing a list, set or dict.
When passing a list of parameter names, the return value will be a
corresponding list of parameter settings. When passing a set of
parameter names, a new dict will be returned, mapping these parameter
names to their settings. Finally, if you pass a dict as parameter,
its values will be set to the current parameter settings corresponding
to its keys.</p>
<p>By passing the special name <code class="docutils literal"><span class="pre">'all'</span></code> as the parameter, you can get a dict
of all existing configuration parameters.</p>
<p>Note that you can request most of the important parameters also using
<a class="reference internal" href="connection.html#pg.Connection.parameter" title="pg.Connection.parameter"><code class="xref py py-meth docutils literal"><span class="pre">Connection.parameter()</span></code></a> which does not involve a database query
like it is the case for <a class="reference internal" href="#pg.DB.get_parameter" title="pg.DB.get_parameter"><code class="xref py py-meth docutils literal"><span class="pre">DB.get_parameter()</span></code></a> and <a class="reference internal" href="#pg.DB.set_parameter" title="pg.DB.set_parameter"><code class="xref py py-meth docutils literal"><span class="pre">DB.set_parameter()</span></code></a>.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.2.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.set_parameter">
<code class="descclassname">DB.</code><code class="descname">set_parameter</code><span class="sig-paren">(</span><em>parameter</em><span class="optional">[</span>, <em>value</em><span class="optional">]</span><span class="optional">[</span>, <em>local</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.set_parameter" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the value of run-time parameters</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>parameter</strong> – the run-time parameter(s) to set</li>
<li><strong>value</strong> – the value to set</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>TypeError</strong> – Invalid parameter type(s)</li>
<li><strong>ValueError</strong> – Invalid value argument(s)</li>
<li><strong>pg.ProgrammingError</strong> – Invalid parameter name(s) or values</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>If the parameter and the value are strings, the run-time parameter
will be set to that value. If no value or <em>None</em> is passed as a value,
then the run-time parameter will be restored to its default value.</p>
<p>You can set several parameters at once by passing a list of parameter
names, together with a single value that all parameters should be
set to or with a corresponding list of values. You can also pass
the parameters as a set if you only provide a single value.
Finally, you can pass a dict with parameter names as keys. In this
case, you should not pass a value, since the values for the parameters
will be taken from the dict.</p>
<p>By passing the special name <code class="docutils literal"><span class="pre">'all'</span></code> as the parameter, you can reset
all existing settable run-time parameters to their default values.</p>
<p>If you set <em>local</em> to <cite>True</cite>, then the command takes effect for only the
current transaction. After <a class="reference internal" href="#pg.DB.commit" title="pg.DB.commit"><code class="xref py py-meth docutils literal"><span class="pre">DB.commit()</span></code></a> or <a class="reference internal" href="#pg.DB.rollback" title="pg.DB.rollback"><code class="xref py py-meth docutils literal"><span class="pre">DB.rollback()</span></code></a>,
the session-level setting takes effect again. Setting <em>local</em> to <cite>True</cite>
will appear to have no effect if it is executed outside a transaction,
since the transaction will end immediately.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.2.</span></p>
</div>
</div>
<div class="section" id="begin-commit-rollback-savepoint-release-transaction-handling">
<h2>begin/commit/rollback/savepoint/release – transaction handling<a class="headerlink" href="#begin-commit-rollback-savepoint-release-transaction-handling" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.begin">
<code class="descclassname">DB.</code><code class="descname">begin</code><span class="sig-paren">(</span><span class="optional">[</span><em>mode</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.begin" title="Permalink to this definition">¶</a></dt>
<dd><p>Begin a transaction</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>mode</strong> (<em>str</em>) – an optional transaction mode such as ‘READ ONLY’</td>
</tr>
</tbody>
</table>
<p>This initiates a transaction block, that is, all following queries
will be executed in a single transaction until <a class="reference internal" href="#pg.DB.commit" title="pg.DB.commit"><code class="xref py py-meth docutils literal"><span class="pre">DB.commit()</span></code></a>
or <a class="reference internal" href="#pg.DB.rollback" title="pg.DB.rollback"><code class="xref py py-meth docutils literal"><span class="pre">DB.rollback()</span></code></a> is called.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.start">
<code class="descclassname">DB.</code><code class="descname">start</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.start" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the same as the <a class="reference internal" href="#pg.DB.begin" title="pg.DB.begin"><code class="xref py py-meth docutils literal"><span class="pre">DB.begin()</span></code></a> method.</p>
</dd></dl>
<dl class="method">
<dt id="pg.DB.commit">
<code class="descclassname">DB.</code><code class="descname">commit</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.commit" title="Permalink to this definition">¶</a></dt>
<dd><p>Commit a transaction</p>
<p>This commits the current transaction. All changes made by the
transaction become visible to others and are guaranteed to be
durable if a crash occurs.</p>
</dd></dl>
<dl class="method">
<dt id="pg.DB.end">
<code class="descclassname">DB.</code><code class="descname">end</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.end" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the same as the <a class="reference internal" href="#pg.DB.commit" title="pg.DB.commit"><code class="xref py py-meth docutils literal"><span class="pre">DB.commit()</span></code></a> method.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.rollback">
<code class="descclassname">DB.</code><code class="descname">rollback</code><span class="sig-paren">(</span><span class="optional">[</span><em>name</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.rollback" title="Permalink to this definition">¶</a></dt>
<dd><p>Roll back a transaction</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>name</strong> (<em>str</em>) – optionally, roll back to the specified savepoint</td>
</tr>
</tbody>
</table>
<p>This rolls back the current transaction and causes all the updates
made by the transaction to be discarded.</p>
</dd></dl>
<dl class="method">
<dt id="pg.DB.abort">
<code class="descclassname">DB.</code><code class="descname">abort</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.abort" title="Permalink to this definition">¶</a></dt>
<dd><p>This is the same as the <a class="reference internal" href="#pg.DB.rollback" title="pg.DB.rollback"><code class="xref py py-meth docutils literal"><span class="pre">DB.rollback()</span></code></a> method.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.2.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.savepoint">
<code class="descclassname">DB.</code><code class="descname">savepoint</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.savepoint" title="Permalink to this definition">¶</a></dt>
<dd><p>Define a new savepoint</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>name</strong> (<em>str</em>) – the name to give to the new savepoint</td>
</tr>
</tbody>
</table>
<p>This establishes a new savepoint within the current transaction.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.release">
<code class="descclassname">DB.</code><code class="descname">release</code><span class="sig-paren">(</span><em>name</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.release" title="Permalink to this definition">¶</a></dt>
<dd><p>Destroy a savepoint</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>name</strong> (<em>str</em>) – the name of the savepoint to destroy</td>
</tr>
</tbody>
</table>
<p>This destroys a savepoint previously defined in the current transaction.</p>
</dd></dl>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
</div>
<div class="section" id="get-get-a-row-from-a-database-table-or-view">
<h2>get – get a row from a database table or view<a class="headerlink" href="#get-get-a-row-from-a-database-table-or-view" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get">
<code class="descclassname">DB.</code><code class="descname">get</code><span class="sig-paren">(</span><em>table</em>, <em>row</em><span class="optional">[</span>, <em>keyname</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a row from a database table or view</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table or view</li>
<li><strong>row</strong> – either a dictionary or the value to be looked up</li>
<li><strong>keyname</strong> (<em>str</em>) – name of field to use as key (optional)</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">A dictionary - the keys are the attribute names,
the values are the row values.</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>pg.ProgrammingError</strong> – table has no primary key or missing privilege</li>
<li><strong>KeyError</strong> – missing key value for the row</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method is the basic mechanism to get a single row. It assumes
that the <em>keyname</em> specifies a unique row. It must be the name of a
single column or a tuple of column names. If <em>keyname</em> is not specified,
then the primary key for the table is used.</p>
<p>If <em>row</em> is a dictionary, then the value for the key is taken from it.
Otherwise, the row must be a single value or a tuple of values
corresponding to the passed <em>keyname</em> or primary key. The fetched row
from the table will be returned as a new dictionary or used to replace
the existing values when row was passed as aa dictionary.</p>
<p>The OID is also put into the dictionary if the table has one, but
in order to allow the caller to work with multiple tables, it is
munged as <code class="docutils literal"><span class="pre">oid(table)</span></code> using the actual name of the table.</p>
<p>Note that since PyGreSQL 5.0 this will return the value of an array
type column as a Python list by default.</p>
</div>
<div class="section" id="insert-insert-a-row-into-a-database-table">
<h2>insert – insert a row into a database table<a class="headerlink" href="#insert-insert-a-row-into-a-database-table" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.insert">
<code class="descclassname">DB.</code><code class="descname">insert</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>row</em><span class="optional">]</span><span class="optional">[</span>, <em>col=val</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.insert" title="Permalink to this definition">¶</a></dt>
<dd><p>Insert a row into a database table</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table</li>
<li><strong>row</strong> (<em>dict</em>) – optional dictionary of values</li>
<li><strong>col</strong> – optional keyword arguments for updating the dictionary</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the inserted values in the database</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">dict</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first last"><strong>pg.ProgrammingError</strong> – missing privilege or conflict</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method inserts a row into a table. If the optional dictionary is
not supplied then the required values must be included as keyword/value
pairs. If a dictionary is supplied then any keywords provided will be
added to or replace the entry in the dictionary.</p>
<p>The dictionary is then reloaded with the values actually inserted in order
to pick up values modified by rules, triggers, etc.</p>
<p>Note that since PyGreSQL 5.0 it is possible to insert a value for an
array type column by passing it as Python list.</p>
</div>
<div class="section" id="update-update-a-row-in-a-database-table">
<h2>update – update a row in a database table<a class="headerlink" href="#update-update-a-row-in-a-database-table" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.update">
<code class="descclassname">DB.</code><code class="descname">update</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>row</em><span class="optional">]</span><span class="optional">[</span>, <em>col=val</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.update" title="Permalink to this definition">¶</a></dt>
<dd><p>Update a row in a database table</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table</li>
<li><strong>row</strong> (<em>dict</em>) – optional dictionary of values</li>
<li><strong>col</strong> – optional keyword arguments for updating the dictionary</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the new row in the database</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">dict</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>pg.ProgrammingError</strong> – table has no primary key or missing privilege</li>
<li><strong>KeyError</strong> – missing key value for the row</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Similar to insert, but updates an existing row. The update is based on
the primary key of the table or the OID value as munged by <a class="reference internal" href="#pg.DB.get" title="pg.DB.get"><code class="xref py py-meth docutils literal"><span class="pre">DB.get()</span></code></a>
or passed as keyword. The OID will take precedence if provided, so that it
is possible to update the primary key itself.</p>
<p>The dictionary is then modified to reflect any changes caused by the
update due to triggers, rules, default values, etc.</p>
<p>Like insert, the dictionary is optional and updates will be performed
on the fields in the keywords. There must be an OID or primary key
either in the dictionary where the OID must be munged, or in the keywords
where it can be simply the string <code class="docutils literal"><span class="pre">'oid'</span></code>.</p>
</div>
<div class="section" id="upsert-insert-a-row-with-conflict-resolution">
<h2>upsert – insert a row with conflict resolution<a class="headerlink" href="#upsert-insert-a-row-with-conflict-resolution" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.upsert">
<code class="descclassname">DB.</code><code class="descname">upsert</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>row</em><span class="optional">]</span><span class="optional">[</span>, <em>col=val</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.upsert" title="Permalink to this definition">¶</a></dt>
<dd><p>Insert a row into a database table with conflict resolution</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table</li>
<li><strong>row</strong> (<em>dict</em>) – optional dictionary of values</li>
<li><strong>col</strong> – optional keyword arguments for specifying the update</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the new row in the database</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">dict</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first last"><strong>pg.ProgrammingError</strong> – table has no primary key or missing privilege</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method inserts a row into a table, but instead of raising a
ProgrammingError exception in case a row with the same primary key already
exists, an update will be executed instead. This will be performed as a
single atomic operation on the database, so race conditions can be avoided.</p>
<p>Like the insert method, the first parameter is the name of the table and the
second parameter can be used to pass the values to be inserted as a dictionary.</p>
<p>Unlike the insert und update statement, keyword parameters are not used to
modify the dictionary, but to specify which columns shall be updated in case
of a conflict, and in which way:</p>
<p>A value of <cite>False</cite> or <cite>None</cite> means the column shall not be updated,
a value of <cite>True</cite> means the column shall be updated with the value that
has been proposed for insertion, i.e. has been passed as value in the
dictionary. Columns that are not specified by keywords but appear as keys
in the dictionary are also updated like in the case keywords had been passed
with the value <cite>True</cite>.</p>
<p>So if in the case of a conflict you want to update every column that has been
passed in the dictionary <cite>d</cite> , you would call <code class="docutils literal"><span class="pre">upsert(table,</span> <span class="pre">d)</span></code>. If you
don’t want to do anything in case of a conflict, i.e. leave the existing row
as it is, call <code class="docutils literal"><span class="pre">upsert(table,</span> <span class="pre">d,</span> <span class="pre">**dict.fromkeys(d))</span></code>.</p>
<p>If you need more fine-grained control of what gets updated, you can also pass
strings in the keyword parameters. These strings will be used as SQL
expressions for the update columns. In these expressions you can refer
to the value that already exists in the table by writing the table prefix
<code class="docutils literal"><span class="pre">included.</span></code> before the column name, and you can refer to the value that
has been proposed for insertion by writing <code class="docutils literal"><span class="pre">excluded.</span></code> as table prefix.</p>
<p>The dictionary is modified in any case to reflect the values in the database
after the operation has completed.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">The method uses the PostgreSQL “upsert” feature which is only available
since PostgreSQL 9.5. With older PostgreSQL versions, you will get a
ProgrammingError if you use this method.</p>
</div>
<div class="versionadded">
<p><span class="versionmodified">New in version 5.0.</span></p>
</div>
</div>
<div class="section" id="query-execute-a-sql-command-string">
<h2>query – execute a SQL command string<a class="headerlink" href="#query-execute-a-sql-command-string" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.query">
<code class="descclassname">DB.</code><code class="descname">query</code><span class="sig-paren">(</span><em>command</em><span class="optional">[</span>, <em>arg1</em><span class="optional">[</span>, <em>arg2</em>, <em>...</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.query" title="Permalink to this definition">¶</a></dt>
<dd><p>Execute a SQL command string</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>command</strong> (<em>str</em>) – SQL command</li>
<li><strong>arg*</strong> – optional positional arguments</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">result values</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="query.html#pg.Query" title="pg.Query"><code class="xref py py-class docutils literal"><span class="pre">Query</span></code></a>, None</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>TypeError</strong> – bad argument type, or too many arguments</li>
<li><strong>TypeError</strong> – invalid connection</li>
<li><strong>ValueError</strong> – empty SQL query or lost connection</li>
<li><strong>pg.ProgrammingError</strong> – error in query</li>
<li><strong>pg.InternalError</strong> – error during query processing</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Similar to the <a class="reference internal" href="connection.html#pg.Connection" title="pg.Connection"><code class="xref py py-class docutils literal"><span class="pre">Connection</span></code></a> function with the same name, except that
positional arguments can be passed either as a single list or tuple, or as
individual positional arguments.</p>
<p>Example:</p>
<div class="highlight-default"><div class="highlight"><pre><span class="n">name</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">"Name? "</span><span class="p">)</span>
<span class="n">phone</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">"Phone? "</span><span class="p">)</span>
<span class="n">rows</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="s">"update employees set phone=$2 where name=$1"</span><span class="p">,</span>
<span class="p">(</span><span class="n">name</span><span class="p">,</span> <span class="n">phone</span><span class="p">))</span><span class="o">.</span><span class="n">getresult</span><span class="p">()[</span><span class="mi">0</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span>
<span class="c"># or</span>
<span class="n">rows</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="s">"update employees set phone=$2 where name=$1"</span><span class="p">,</span>
<span class="n">name</span><span class="p">,</span> <span class="n">phone</span><span class="p">)</span><span class="o">.</span><span class="n">getresult</span><span class="p">()[</span><span class="mi">0</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
</div>
<div class="section" id="query-formatted-execute-a-formatted-sql-command-string">
<h2>query_formatted – execute a formatted SQL command string<a class="headerlink" href="#query-formatted-execute-a-formatted-sql-command-string" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.query_formatted">
<code class="descclassname">DB.</code><code class="descname">query_formatted</code><span class="sig-paren">(</span><em>command</em>, <em>parameters</em><span class="optional">[</span>, <em>types</em><span class="optional">]</span><span class="optional">[</span>, <em>inline</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.query_formatted" title="Permalink to this definition">¶</a></dt>
<dd><p>Execute a formatted SQL command string</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>command</strong> (<em>str</em>) – SQL command</li>
<li><strong>parameters</strong> (<em>tuple, list or dict</em>) – the values of the parameters for the SQL command</li>
<li><strong>types</strong> (<em>tuple, list or dict</em>) – optionally, the types of the parameters</li>
<li><strong>inline</strong> (<em>bool</em>) – whether the parameters should be passed in the SQL</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="query.html#pg.Query" title="pg.Query"><code class="xref py py-class docutils literal"><span class="pre">Query</span></code></a>, None</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>TypeError</strong> – bad argument type, or too many arguments</li>
<li><strong>TypeError</strong> – invalid connection</li>
<li><strong>ValueError</strong> – empty SQL query or lost connection</li>
<li><strong>pg.ProgrammingError</strong> – error in query</li>
<li><strong>pg.InternalError</strong> – error during query processing</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Similar to <a class="reference internal" href="#pg.DB.query" title="pg.DB.query"><code class="xref py py-meth docutils literal"><span class="pre">DB.query()</span></code></a>, but using Python format placeholders of the form
<code class="docutils literal"><span class="pre">%s</span></code> or <code class="docutils literal"><span class="pre">%(names)s</span></code> instead of PostgreSQL placeholders of the form <code class="docutils literal"><span class="pre">$1</span></code>.
The parameters must be passed as a tuple, list or dict. You can also pass a
corresponding tuple, list or dict of database types in order to format the
parameters properly in case there is ambiguity.</p>
<p>If you set <em>inline</em> to True, the parameters will be sent to the database
embedded in the SQL command, otherwise they will be sent separately.</p>
<p>Example:</p>
<div class="highlight-default"><div class="highlight"><pre><span class="n">name</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">"Name? "</span><span class="p">)</span>
<span class="n">phone</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">"Phone? "</span><span class="p">)</span>
<span class="n">rows</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">query_formatted</span><span class="p">(</span>
<span class="s">"update employees set phone=%s where name=%s"</span><span class="p">,</span>
<span class="p">(</span><span class="n">phone</span><span class="p">,</span> <span class="n">name</span><span class="p">))</span><span class="o">.</span><span class="n">getresult</span><span class="p">()[</span><span class="mi">0</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span>
<span class="c"># or</span>
<span class="n">rows</span> <span class="o">=</span> <span class="n">db</span><span class="o">.</span><span class="n">query_formatted</span><span class="p">(</span>
<span class="s">"update employees set phone=%(phone)s where name=%(name)s"</span><span class="p">,</span>
<span class="nb">dict</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="n">name</span><span class="p">,</span> <span class="n">phone</span><span class="o">=</span><span class="n">phone</span><span class="p">))</span><span class="o">.</span><span class="n">getresult</span><span class="p">()[</span><span class="mi">0</span><span class="p">][</span><span class="mi">0</span><span class="p">]</span>
</pre></div>
</div>
</div>
<div class="section" id="clear-clear-row-values-in-memory">
<h2>clear – clear row values in memory<a class="headerlink" href="#clear-clear-row-values-in-memory" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.clear">
<code class="descclassname">DB.</code><code class="descname">clear</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>row</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.clear" title="Permalink to this definition">¶</a></dt>
<dd><p>Clear row values in memory</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table</li>
<li><strong>row</strong> (<em>dict</em>) – optional dictionary of values</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">an empty row</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first last">dict</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method clears all the attributes to values determined by the types.
Numeric types are set to 0, Booleans are set to <em>False</em>, and everything
else is set to the empty string. If the row argument is present, it is
used as the row dictionary and any entries matching attribute names are
cleared with everything else left unchanged.</p>
<p>If the dictionary is not supplied a new one is created.</p>
</div>
<div class="section" id="delete-delete-a-row-from-a-database-table">
<h2>delete – delete a row from a database table<a class="headerlink" href="#delete-delete-a-row-from-a-database-table" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.delete">
<code class="descclassname">DB.</code><code class="descname">delete</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>row</em><span class="optional">]</span><span class="optional">[</span>, <em>col=val</em>, <em>...</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.delete" title="Permalink to this definition">¶</a></dt>
<dd><p>Delete a row from a database table</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – name of table</li>
<li><strong>d</strong> (<em>dict</em>) – optional dictionary of values</li>
<li><strong>col</strong> – optional keyword arguments for updating the dictionary</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">None</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>pg.ProgrammingError</strong> – table has no primary key,
row is still referenced or missing privilege</li>
<li><strong>KeyError</strong> – missing key value for the row</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method deletes the row from a table. It deletes based on the
primary key of the table or the OID value as munged by <a class="reference internal" href="#pg.DB.get" title="pg.DB.get"><code class="xref py py-meth docutils literal"><span class="pre">DB.get()</span></code></a>
or passed as keyword. The OID will take precedence if provided.</p>
<p>The return value is the number of deleted rows (i.e. 0 if the row did not
exist and 1 if the row was deleted).</p>
<p>Note that if the row cannot be deleted because e.g. it is still referenced
by another table, this method will raise a ProgrammingError.</p>
</div>
<div class="section" id="truncate-quickly-empty-database-tables">
<h2>truncate – quickly empty database tables<a class="headerlink" href="#truncate-quickly-empty-database-tables" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.truncate">
<code class="descclassname">DB.</code><code class="descname">truncate</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>restart</em><span class="optional">]</span><span class="optional">[</span>, <em>cascade</em><span class="optional">]</span><span class="optional">[</span>, <em>only</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.truncate" title="Permalink to this definition">¶</a></dt>
<dd><p>Empty a table or set of tables</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>table</strong> (<em>str, list or set</em>) – the name of the table(s)</li>
<li><strong>restart</strong> (<em>bool</em>) – whether table sequences should be restarted</li>
<li><strong>cascade</strong> (<em>bool</em>) – whether referenced tables should also be truncated</li>
<li><strong>only</strong> (<em>bool or list</em>) – whether only parent tables should be truncated</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method quickly removes all rows from the given table or set
of tables. It has the same effect as an unqualified DELETE on each
table, but since it does not actually scan the tables it is faster.
Furthermore, it reclaims disk space immediately, rather than requiring
a subsequent VACUUM operation. This is most useful on large tables.</p>
<p>If <em>restart</em> is set to <cite>True</cite>, sequences owned by columns of the truncated
table(s) are automatically restarted. If <em>cascade</em> is set to <cite>True</cite>, it
also truncates all tables that have foreign-key references to any of
the named tables. If the parameter <em>only</em> is not set to <cite>True</cite>, all the
descendant tables (if any) will also be truncated. Optionally, a <code class="docutils literal"><span class="pre">*</span></code>
can be specified after the table name to explicitly indicate that
descendant tables are included. If the parameter <em>table</em> is a list,
the parameter <em>only</em> can also be a list of corresponding boolean values.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.2.</span></p>
</div>
</div>
<div class="section" id="get-as-list-dict-read-a-table-as-a-list-or-dictionary">
<h2>get_as_list/dict – read a table as a list or dictionary<a class="headerlink" href="#get-as-list-dict-read-a-table-as-a-list-or-dictionary" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.get_as_list">
<code class="descclassname">DB.</code><code class="descname">get_as_list</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>what</em><span class="optional">]</span><span class="optional">[</span>, <em>where</em><span class="optional">]</span><span class="optional">[</span>, <em>order</em><span class="optional">]</span><span class="optional">[</span>, <em>limit</em><span class="optional">]</span><span class="optional">[</span>, <em>offset</em><span class="optional">]</span><span class="optional">[</span>, <em>scalar</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_as_list" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a table as a list</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – the name of the table (the FROM clause)</li>
<li><strong>what</strong> (<em>str, list, tuple or None</em>) – column(s) to be returned (the SELECT clause)</li>
<li><strong>where</strong> (<em>str, list, tuple or None</em>) – conditions(s) to be fulfilled (the WHERE clause)</li>
<li><strong>order</strong> (<em>str, list, tuple, False or None</em>) – column(s) to sort by (the ORDER BY clause)</li>
<li><strong>limit</strong> (<em>int</em>) – maximum number of rows returned (the LIMIT clause)</li>
<li><strong>offset</strong> (<em>int</em>) – number of rows to be skipped (the OFFSET clause)</li>
<li><strong>scalar</strong> (<em>bool</em>) – whether only the first column shall be returned</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the content of the table as a list</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">list</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><p class="first last"><strong>TypeError</strong> – the table name has not been specified</p>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This gets a convenient representation of the table as a list of named tuples
in Python. You only need to pass the name of the table (or any other SQL
expression returning rows). Note that by default this will return the full
content of the table which can be huge and overflow your memory. However, you
can control the amount of data returned using the other optional parameters.</p>
<p>The parameter <em>what</em> can restrict the query to only return a subset of the
table columns. The parameter <em>where</em> can restrict the query to only return a
subset of the table rows. The specified SQL expressions all need to be
fulfilled for a row to get into the result. The parameter <em>order</em> specifies
the ordering of the rows. If no ordering is specified, the result will be
ordered by the primary key(s) or all columns if no primary key exists.
You can set <em>order</em> to <em>False</em> if you don’t care about the ordering.
The parameters <em>limit</em> and <em>offset</em> specify the maximum number of rows
returned and a number of rows skipped over.</p>
<p>If you set the <em>scalar</em> option to <em>True</em>, then instead of the named tuples
you will get the first items of these tuples. This is useful if the result
has only one column anyway.</p>
<dl class="method">
<dt id="pg.DB.get_as_dict">
<code class="descclassname">DB.</code><code class="descname">get_as_dict</code><span class="sig-paren">(</span><em>table</em><span class="optional">[</span>, <em>keyname</em><span class="optional">]</span><span class="optional">[</span>, <em>what</em><span class="optional">]</span><span class="optional">[</span>, <em>where</em><span class="optional">]</span><span class="optional">[</span>, <em>order</em><span class="optional">]</span><span class="optional">[</span>, <em>limit</em><span class="optional">]</span><span class="optional">[</span>, <em>offset</em><span class="optional">]</span><span class="optional">[</span>, <em>scalar</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.get_as_dict" title="Permalink to this definition">¶</a></dt>
<dd><p>Get a table as a dictionary</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first simple">
<li><strong>table</strong> (<em>str</em>) – the name of the table (the FROM clause)</li>
<li><strong>keyname</strong> (<em>str, list, tuple or None</em>) – column(s) to be used as key(s) of the dictionary</li>
<li><strong>what</strong> (<em>str, list, tuple or None</em>) – column(s) to be returned (the SELECT clause)</li>
<li><strong>where</strong> (<em>str, list, tuple or None</em>) – conditions(s) to be fulfilled (the WHERE clause)</li>
<li><strong>order</strong> (<em>str, list, tuple, False or None</em>) – column(s) to sort by (the ORDER BY clause)</li>
<li><strong>limit</strong> (<em>int</em>) – maximum number of rows returned (the LIMIT clause)</li>
<li><strong>offset</strong> (<em>int</em>) – number of rows to be skipped (the OFFSET clause)</li>
<li><strong>scalar</strong> (<em>bool</em>) – whether only the first column shall be returned</li>
</ul>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body"><p class="first">the content of the table as a list</p>
</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body"><p class="first">dict or OrderedDict</p>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Raises:</th><td class="field-body"><ul class="first last simple">
<li><strong>TypeError</strong> – the table name has not been specified</li>
<li><strong>KeyError</strong> – keyname(s) are invalid or not part of the result</li>
<li><strong>pg.ProgrammingError</strong> – no keyname(s) and table has no primary key</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method is similar to <a class="reference internal" href="#pg.DB.get_as_list" title="pg.DB.get_as_list"><code class="xref py py-meth docutils literal"><span class="pre">DB.get_as_list()</span></code></a>, but returns the table as
a Python dict instead of a Python list, which can be even more convenient.
The primary key column(s) of the table will be used as the keys of the
dictionary, while the other column(s) will be the corresponding values.
The keys will be named tuples if the table has a composite primary key.
The rows will be also named tuples unless the <em>scalar</em> option has been set
to <em>True</em>. With the optional parameter <em>keyname</em> you can specify a different
set of columns to be used as the keys of the dictionary.</p>
<p>If the Python version supports it, the dictionary will be an <em>OrderedDict</em>
using the order specified with the <em>order</em> parameter or the key column(s)
if not specified. You can set <em>order</em> to <em>False</em> if you don’t care about the
ordering. In this case the returned dictionary will be an ordinary one.</p>
</div>
<div class="section" id="escape-literal-identifier-string-bytea-escape-for-sql">
<h2>escape_literal/identifier/string/bytea – escape for SQL<a class="headerlink" href="#escape-literal-identifier-string-bytea-escape-for-sql" title="Permalink to this headline">¶</a></h2>
<p>The following methods escape text or binary strings so that they can be
inserted directly into an SQL command. Except for <code class="xref py py-meth docutils literal"><span class="pre">DB.escape_byte()</span></code>,
you don’t need to call these methods for the strings passed as parameters
to <a class="reference internal" href="#pg.DB.query" title="pg.DB.query"><code class="xref py py-meth docutils literal"><span class="pre">DB.query()</span></code></a>. You also don’t need to call any of these methods
when storing data using <a class="reference internal" href="#pg.DB.insert" title="pg.DB.insert"><code class="xref py py-meth docutils literal"><span class="pre">DB.insert()</span></code></a> and similar.</p>
<dl class="method">
<dt id="pg.DB.escape_literal">
<code class="descclassname">DB.</code><code class="descname">escape_literal</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.escape_literal" title="Permalink to this definition">¶</a></dt>
<dd><p>Escape a string for use within SQL as a literal constant</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>string</strong> (<em>str</em>) – the string that is to be escaped</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">the escaped string</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method escapes a string for use within an SQL command. This is useful
when inserting data values as literal constants in SQL commands. Certain
characters (such as quotes and backslashes) must be escaped to prevent them
from being interpreted specially by the SQL parser.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.escape_identifier">
<code class="descclassname">DB.</code><code class="descname">escape_identifier</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.escape_identifier" title="Permalink to this definition">¶</a></dt>
<dd><p>Escape a string for use within SQL as an identifier</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>string</strong> (<em>str</em>) – the string that is to be escaped</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">the escaped string</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method escapes a string for use as an SQL identifier, such as a table,
column, or function name. This is useful when a user-supplied identifier
might contain special characters that would otherwise not be interpreted
as part of the identifier by the SQL parser, or when the identifier might
contain upper case characters whose case should be preserved.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.escape_string">
<code class="descclassname">DB.</code><code class="descname">escape_string</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.escape_string" title="Permalink to this definition">¶</a></dt>
<dd><p>Escape a string for use within SQL</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>string</strong> (<em>str</em>) – the string that is to be escaped</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">the escaped string</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Similar to the module function <a class="reference internal" href="module.html#pg.escape_string" title="pg.escape_string"><code class="xref py py-func docutils literal"><span class="pre">pg.escape_string()</span></code></a> with the same name,
but the behavior of this method is adjusted depending on the connection
properties (such as character encoding).</p>
<dl class="method">
<dt id="pg.DB.escape_bytea">
<code class="descclassname">DB.</code><code class="descname">escape_bytea</code><span class="sig-paren">(</span><em>datastring</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.escape_bytea" title="Permalink to this definition">¶</a></dt>
<dd><p>Escape binary data for use within SQL as type <code class="docutils literal"><span class="pre">bytea</span></code></p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>datastring</strong> (<em>str</em>) – string containing the binary data that is to be escaped</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">the escaped string</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Similar to the module function <a class="reference internal" href="module.html#pg.escape_bytea" title="pg.escape_bytea"><code class="xref py py-func docutils literal"><span class="pre">pg.escape_bytea()</span></code></a> with the same name,
but the behavior of this method is adjusted depending on the connection
properties (in particular, whether standard-conforming strings are enabled).</p>
</div>
<div class="section" id="unescape-bytea-unescape-data-retrieved-from-the-database">
<h2>unescape_bytea – unescape data retrieved from the database<a class="headerlink" href="#unescape-bytea-unescape-data-retrieved-from-the-database" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.unescape_bytea">
<code class="descclassname">DB.</code><code class="descname">unescape_bytea</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.unescape_bytea" title="Permalink to this definition">¶</a></dt>
<dd><p>Unescape <code class="docutils literal"><span class="pre">bytea</span></code> data that has been retrieved as text</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>datastring</strong> – the <code class="docutils literal"><span class="pre">bytea</span></code> data string that has been retrieved as text</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">byte string containing the binary data</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">bytes</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>Converts an escaped string representation of binary data stored as <code class="docutils literal"><span class="pre">bytea</span></code>
into the raw byte string representing the binary data – this is the reverse
of <a class="reference internal" href="#pg.DB.escape_bytea" title="pg.DB.escape_bytea"><code class="xref py py-meth docutils literal"><span class="pre">DB.escape_bytea()</span></code></a>. Since the <a class="reference internal" href="query.html#pg.Query" title="pg.Query"><code class="xref py py-class docutils literal"><span class="pre">Query</span></code></a> results will already
return unescaped byte strings, you normally don’t have to use this method.</p>
</div>
<div class="section" id="encode-decode-json-encode-and-decode-json-data">
<h2>encode/decode_json – encode and decode JSON data<a class="headerlink" href="#encode-decode-json-encode-and-decode-json-data" title="Permalink to this headline">¶</a></h2>
<p>The following methods can be used to encode end decode data in
<a class="reference external" href="http://www.json.org/">JSON</a> format.</p>
<dl class="method">
<dt id="pg.DB.encode_json">
<code class="descclassname">DB.</code><code class="descname">encode_json</code><span class="sig-paren">(</span><em>obj</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.encode_json" title="Permalink to this definition">¶</a></dt>
<dd><p>Encode a Python object for use within SQL as type <code class="docutils literal"><span class="pre">json</span></code> or <code class="docutils literal"><span class="pre">jsonb</span></code></p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>obj</strong> (<em>dict, list or None</em>) – Python object that shall be encoded to JSON format</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">string representation of the Python object in JSON format</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">str</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method serializes a Python object into a JSON formatted string that can
be used within SQL. You don’t need to use this method on the data stored
with <a class="reference internal" href="#pg.DB.insert" title="pg.DB.insert"><code class="xref py py-meth docutils literal"><span class="pre">DB.insert()</span></code></a> and similar, only if you store the data directly as
part of an SQL command or parameter with <a class="reference internal" href="#pg.DB.query" title="pg.DB.query"><code class="xref py py-meth docutils literal"><span class="pre">DB.query()</span></code></a>. This is the same
as the <code class="xref py py-func docutils literal"><span class="pre">json.dumps()</span></code> function from the standard library.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 5.0.</span></p>
</div>
<dl class="method">
<dt id="pg.DB.decode_json">
<code class="descclassname">DB.</code><code class="descname">decode_json</code><span class="sig-paren">(</span><em>string</em><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.decode_json" title="Permalink to this definition">¶</a></dt>
<dd><p>Decode <code class="docutils literal"><span class="pre">json</span></code> or <code class="docutils literal"><span class="pre">jsonb</span></code> data that has been retrieved as text</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>string</strong> (<em>str</em>) – JSON formatted string shall be decoded into a Python object</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">Python object representing the JSON formatted string</td>
</tr>
<tr class="field-odd field"><th class="field-name">Return type:</th><td class="field-body">dict, list or None</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method deserializes a JSON formatted string retrieved as text from the
database to a Python object. You normally don’t need to use this method as
JSON data is automatically decoded by PyGreSQL. If you don’t want the data
to be decoded, then you can cast <code class="docutils literal"><span class="pre">json</span></code> or <code class="docutils literal"><span class="pre">jsonb</span></code> columns to <code class="docutils literal"><span class="pre">text</span></code>
in PostgreSQL or you can set the decoding function to <em>None</em> or a different
function using <a class="reference internal" href="module.html#pg.set_jsondecode" title="pg.set_jsondecode"><code class="xref py py-func docutils literal"><span class="pre">pg.set_jsondecode()</span></code></a>. By default this is the same as
the <code class="xref py py-func docutils literal"><span class="pre">json.dumps()</span></code> function from the standard library.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 5.0.</span></p>
</div>
</div>
<div class="section" id="use-regtypes-determine-use-of-regular-type-names">
<h2>use_regtypes – determine use of regular type names<a class="headerlink" href="#use-regtypes-determine-use-of-regular-type-names" title="Permalink to this headline">¶</a></h2>
<dl class="method">
<dt id="pg.DB.use_regtypes">
<code class="descclassname">DB.</code><code class="descname">use_regtypes</code><span class="sig-paren">(</span><span class="optional">[</span><em>regtypes</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.use_regtypes" title="Permalink to this definition">¶</a></dt>
<dd><p>Determine whether regular type names shall be used</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><strong>regtypes</strong> (<em>bool</em>) – if passed, set whether regular type names shall be used</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns:</th><td class="field-body">whether regular type names are used</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>The <a class="reference internal" href="#pg.DB.get_attnames" title="pg.DB.get_attnames"><code class="xref py py-meth docutils literal"><span class="pre">DB.get_attnames()</span></code></a> method can return either simplified “classic”
type names (the default) or more specific “regular” type names. Which kind
of type names is used can be changed by calling <code class="xref py py-meth docutils literal"><span class="pre">DB.get_regtypes()</span></code>.
If you pass a boolean, it sets whether regular type names shall be used.
The method can also be used to check through its return value whether
currently regular type names are used.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.</span></p>
</div>
</div>
<div class="section" id="notification-handler-create-a-notification-handler">
<h2>notification_handler – create a notification handler<a class="headerlink" href="#notification-handler-create-a-notification-handler" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="pg.DB.notification_handler">
<em class="property">class </em><code class="descclassname">DB.</code><code class="descname">notification_handler</code><span class="sig-paren">(</span><em>event</em>, <em>callback</em><span class="optional">[</span>, <em>arg_dict</em><span class="optional">]</span><span class="optional">[</span>, <em>timeout</em><span class="optional">]</span><span class="optional">[</span>, <em>stop_event</em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#pg.DB.notification_handler" title="Permalink to this definition">¶</a></dt>
<dd><p>Create a notification handler instance</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><strong>event</strong> (<em>str</em>) – the name of an event to listen for</li>
<li><strong>callback</strong> – a callback function</li>
<li><strong>arg_dict</strong> (<em>dict</em>) – an optional dictionary for passing arguments</li>
<li><strong>timeout</strong> (<em>int, float or None</em>) – the time-out when waiting for notifications</li>
<li><strong>stop_event</strong> (<em>str</em>) – an optional different name to be used as stop event</li>
</ul>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<p>This method creates a <a class="reference internal" href="notification.html#pg.NotificationHandler" title="pg.NotificationHandler"><code class="xref py py-class docutils literal"><span class="pre">pg.NotificationHandler</span></code></a> object using the
<a class="reference internal" href="#pg.DB" title="pg.DB"><code class="xref py py-class docutils literal"><span class="pre">DB</span></code></a> connection as explained under <a class="reference internal" href="notification.html"><span class="doc">The Notification Handler</span></a>.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 4.1.1.</span></p>
</div>
</div>
<div class="section" id="attributes-of-the-db-wrapper-class">
<h2>Attributes of the DB wrapper class<a class="headerlink" href="#attributes-of-the-db-wrapper-class" title="Permalink to this headline">¶</a></h2>
<dl class="attribute">
<dt id="pg.DB.db">
<code class="descclassname">DB.</code><code class="descname">db</code><a class="headerlink" href="#pg.DB.db" title="Permalink to this definition">¶</a></dt>
<dd><p>The wrapped <a class="reference internal" href="connection.html#pg.Connection" title="pg.Connection"><code class="xref py py-class docutils literal"><span class="pre">Connection</span></code></a> object</p>
</dd></dl>
<p>You normally don’t need this, since all of the members can be accessed
from the <a class="reference internal" href="#pg.DB" title="pg.DB"><code class="xref py py-class docutils literal"><span class="pre">DB</span></code></a> wrapper class as well.</p>
<dl class="attribute">
<dt id="pg.DB.dbname">
<code class="descclassname">DB.</code><code class="descname">dbname</code><a class="headerlink" href="#pg.DB.dbname" title="Permalink to this definition">¶</a></dt>
<dd><p>The name of the database that the connection is using</p>
</dd></dl>
<dl class="attribute">
<dt id="pg.DB.dbtypes">
<code class="descclassname">DB.</code><code class="descname">dbtypes</code><a class="headerlink" href="#pg.DB.dbtypes" title="Permalink to this definition">¶</a></dt>
<dd><p>A dictionary with the various type names for the PostgreSQL types</p>
</dd></dl>
<p>This can be used for getting more information on the PostgreSQL database
types or changing the typecast functions used for the connection. See the
description of the <a class="reference internal" href="db_types.html#pg.DbTypes" title="pg.DbTypes"><code class="xref py py-class docutils literal"><span class="pre">DbTypes</span></code></a> class for details.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 5.0.</span></p>
</div>
<dl class="attribute">
<dt id="pg.DB.adapter">
<code class="descclassname">DB.</code><code class="descname">adapter</code><a class="headerlink" href="#pg.DB.adapter" title="Permalink to this definition">¶</a></dt>
<dd><p>A class with some helper functions for adapting parameters</p>
</dd></dl>
<p>This can be used for building queries with parameters. You normally will
not need this, as you can use the <a class="reference internal" href="#pg.DB.query_formatted" title="pg.DB.query_formatted"><code class="xref py py-class docutils literal"><span class="pre">DB.query_formatted</span></code></a> method.</p>
<div class="versionadded">
<p><span class="versionmodified">New in version 5.0.</span></p>
</div>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<p class="logo"><a href="../index.html" title="contents/index">
<img class="logo" src="../../_static/pygresql.png" alt="Logo"/>
</a></p><div class="sphinxlocaltoc">
<h3><a href="../../index.html">Page contents</a></h3>
<ul>
<li><a class="reference internal" href="#">The DB wrapper class</a><ul>
<li><a class="reference internal" href="#initialization">Initialization</a></li>
<li><a class="reference internal" href="#pkey-return-the-primary-key-of-a-table">pkey – return the primary key of a table</a></li>
<li><a class="reference internal" href="#get-databases-get-list-of-databases-in-the-system">get_databases – get list of databases in the system</a></li>
<li><a class="reference internal" href="#get-relations-get-list-of-relations-in-connected-database">get_relations – get list of relations in connected database</a></li>
<li><a class="reference internal" href="#get-tables-get-list-of-tables-in-connected-database">get_tables – get list of tables in connected database</a></li>
<li><a class="reference internal" href="#get-attnames-get-the-attribute-names-of-a-table">get_attnames – get the attribute names of a table</a></li>
<li><a class="reference internal" href="#has-table-privilege-check-table-privilege">has_table_privilege – check table privilege</a></li>
<li><a class="reference internal" href="#get-set-parameter-get-or-set-run-time-parameters">get/set_parameter – get or set run-time parameters</a></li>
<li><a class="reference internal" href="#begin-commit-rollback-savepoint-release-transaction-handling">begin/commit/rollback/savepoint/release – transaction handling</a></li>
<li><a class="reference internal" href="#get-get-a-row-from-a-database-table-or-view">get – get a row from a database table or view</a></li>
<li><a class="reference internal" href="#insert-insert-a-row-into-a-database-table">insert – insert a row into a database table</a></li>
<li><a class="reference internal" href="#update-update-a-row-in-a-database-table">update – update a row in a database table</a></li>
<li><a class="reference internal" href="#upsert-insert-a-row-with-conflict-resolution">upsert – insert a row with conflict resolution</a></li>
<li><a class="reference internal" href="#query-execute-a-sql-command-string">query – execute a SQL command string</a></li>
<li><a class="reference internal" href="#query-formatted-execute-a-formatted-sql-command-string">query_formatted – execute a formatted SQL command string</a></li>
<li><a class="reference internal" href="#clear-clear-row-values-in-memory">clear – clear row values in memory</a></li>
<li><a class="reference internal" href="#delete-delete-a-row-from-a-database-table">delete – delete a row from a database table</a></li>
<li><a class="reference internal" href="#truncate-quickly-empty-database-tables">truncate – quickly empty database tables</a></li>
<li><a class="reference internal" href="#get-as-list-dict-read-a-table-as-a-list-or-dictionary">get_as_list/dict – read a table as a list or dictionary</a></li>
<li><a class="reference internal" href="#escape-literal-identifier-string-bytea-escape-for-sql">escape_literal/identifier/string/bytea – escape for SQL</a></li>
<li><a class="reference internal" href="#unescape-bytea-unescape-data-retrieved-from-the-database">unescape_bytea – unescape data retrieved from the database</a></li>
<li><a class="reference internal" href="#encode-decode-json-encode-and-decode-json-data">encode/decode_json – encode and decode JSON data</a></li>
<li><a class="reference internal" href="#use-regtypes-determine-use-of-regular-type-names">use_regtypes – determine use of regular type names</a></li>
<li><a class="reference internal" href="#notification-handler-create-a-notification-handler">notification_handler – create a notification handler</a></li>
<li><a class="reference internal" href="#attributes-of-the-db-wrapper-class">Attributes of the DB wrapper class</a></li>
</ul>
</li>
</ul>
</div>
<div class="sphinxprev">
<h4>Previous page</h4>
<p class="topless"><a href="connection.html"
title="Previous page">← Connection – The connection object</a></p>
</div>
<div class="sphinxnext">
<h4>Next page</h4>
<p class="topless"><a href="query.html"
title="Next page">→ Query methods</a></p>
</div>
<div role="note" aria-label="source link">
<h3>This Page</h3>
<ul class="this-page-menu">
<li><a href="../../_sources/contents/pg/db_wrapper.txt"
rel="nofollow">Show Source</a></li>
</ul>
</div>
<div id="searchbox" style="display: none" role="search">
<h3>Quick search</h3>
<form class="search" action="../../search.html" method="get">
<input type="text" name="q" />
<input type="submit" value="Go" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
<script type="text/javascript">$('#searchbox').show(0);</script>
</div>
</div>
<div class="clearer"></div>
</div>
<div class="relbar-bottom">
<div class="related" role="navigation" aria-label="related navigation">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../../genindex.html" title="General Index"
>index</a></li>
<li class="right" >
<a href="../../py-modindex.html" title="Python Module Index"
>modules</a> </li>
<li class="right" >
<a href="query.html" title="Query methods"
>next</a> </li>
<li class="right" >
<a href="connection.html" title="Connection – The connection object"
>previous</a> </li>
<li><a href="../index.html">PyGreSQL 5.0 documentation</a> »</li>
<li class="nav-item nav-item-1"><a href="index.html" ><code class="docutils literal"><span class="pre">pg</span></code> — The Classic PyGreSQL Interface</a> »</li>
</ul>
</div>
</div>
<div class="footer" role="contentinfo">
© <a href="../../copyright.html">Copyright</a> 2016, The PyGreSQL team.
Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.4.1.
</div>
<!-- cloud_sptheme 1.4 -->
</body>
</html>
|
