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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML
><HEAD
><TITLE
>Query Targets</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet version 1.19"><LINK
REL="HOME"
TITLE="PostgreSQL User's Guide"
HREF="user.html"><LINK
REL="UP"
TITLE="Type Conversion"
HREF="typeconv.html"><LINK
REL="PREVIOUS"
TITLE="Functions"
HREF="typeconv2629.html"><LINK
REL="NEXT"
TITLE="UNION Queries"
HREF="typeconv2704.html"></HEAD
><BODY
BGCOLOR="#FFFFFF"
TEXT="#000000"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>PostgreSQL User's Guide</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="typeconv2629.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 8. Type Conversion</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="typeconv2704.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
CLASS="SECT1"
><A
NAME="AEN2683"
>Query Targets</A
></H1
><P
></P
><DIV
CLASS="PROCEDURE"
><P
><B
>Target Evaluation</B
></P
><OL
TYPE="1"
><LI
><P
>Check for an exact match with the target. </P
></LI
><LI
><P
>Try to coerce the expression directly to the target type if necessary. </P
></LI
><LI
><P
>If the target is a fixed-length type (e.g. <SPAN
CLASS="TYPE"
>char</SPAN
> or <SPAN
CLASS="TYPE"
>varchar</SPAN
>
declared with a length) then try to find a sizing function of the same name
as the type taking two arguments, the first the type name and the second an
integer length. </P
></LI
></OL
></DIV
><H2
CLASS="SECT2"
><A
NAME="AEN2696"
>Examples</A
></H2
><H3
CLASS="SECT3"
><A
NAME="AEN2698"
><SPAN
CLASS="TYPE"
>varchar</SPAN
> Storage</A
></H3
><P
>For a target column declared as <SPAN
CLASS="TYPE"
>varchar(4)</SPAN
> the following query
ensures that the target is sized correctly:
<PRE
CLASS="PROGRAMLISTING"
>tgl=> CREATE TABLE vv (v varchar(4));
CREATE
tgl=> INSERT INTO vv SELECT 'abc' || 'def';
INSERT 392905 1
tgl=> select * from vv;
v
----
abcd
(1 row)</PRE
>
</P
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="typeconv2629.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="user.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="typeconv2704.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Functions</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="typeconv.html"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>UNION Queries</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>
|
