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
|
-- Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
--
-- This program is free software; you can redistribute it and/or modify
-- it under the terms of the GNU General Public License as published by
-- the Free Software Foundation; version 2 of the License.
--
-- This program is distributed in the hope that it will be useful,
-- but WITHOUT ANY WARRANTY; without even the implied warranty of
-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-- GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License
-- along with this program; if not, write to the Free Software
-- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
DROP PROCEDURE IF EXISTS table_exists;
DELIMITER $$
CREATE DEFINER='mariadb.sys'@'localhost' PROCEDURE table_exists (
IN in_db VARCHAR(64), IN in_table VARCHAR(64),
OUT out_exists ENUM('', 'BASE TABLE', 'VIEW', 'TEMPORARY', 'SEQUENCE', 'SYSTEM VIEW')
)
COMMENT '
Description
-----------
Tests whether the table specified in in_db and in_table exists either as a regular
table, or as a temporary table. The returned value corresponds to the table that
will be used, so if there''s both a temporary and a permanent table with the given
name, then ''TEMPORARY'' will be returned.
Parameters
-----------
in_db (VARCHAR(64)):
The database name to check for the existence of the table in.
in_table (VARCHAR(64)):
The name of the table to check the existence of.
out_exists ENUM('''', ''BASE TABLE'', ''VIEW'', ''TEMPORARY''):
The return value: whether the table exists. The value is one of:
* '''' - the table does not exist neither as a base table, view, sequence nor temporary table.
* ''BASE TABLE'' - the table name exists as a permanent base table table.
* ''VIEW'' - the table name exists as a view.
* ''TEMPORARY'' - the table name exists as a temporary table.
* ''SEQUENCE'' - the table name exists as a sequence.
* ''SYSTEM VIEW'' - the table name exists as a system view.
Example
--------
mysql> CREATE DATABASE db1;
Query OK, 1 row affected (0.07 sec)
mysql> use db1;
Database changed
mysql> CREATE TABLE t1 (id INT PRIMARY KEY);
Query OK, 0 rows affected (0.08 sec)
mysql> CREATE TABLE t2 (id INT PRIMARY KEY);
Query OK, 0 rows affected (0.08 sec)
mysql> CREATE view v_t1 AS SELECT * FROM t1;
Query OK, 0 rows affected (0.00 sec)
mysql> CREATE TEMPORARY TABLE t1 (id INT PRIMARY KEY);
Query OK, 0 rows affected (0.00 sec)
mysql> CALL sys.table_exists(''db1'', ''t1'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.00 sec)
+------------+
| @exists |
+------------+
| TEMPORARY |
+------------+
1 row in set (0.00 sec)
mysql> CALL sys.table_exists(''db1'', ''t2'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.00 sec)
+------------+
| @exists |
+------------+
| BASE TABLE |
+------------+
1 row in set (0.01 sec)
mysql> CALL sys.table_exists(''db1'', ''v_t1'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.00 sec)
+---------+
| @exists |
+---------+
| VIEW |
+---------+
1 row in set (0.00 sec)
MariaDB [sys]> CALL sys.table_exists(''db1'', ''s'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.006 sec)
+----------+
| @exists |
+----------+
| SEQUENCE |
+----------+
1 row in set (0.000 sec)
MariaDB [sys]> CALL table_exists(''information_schema'', ''user_variables'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.003 sec)
+-------------+
| @exists |
+-------------+
| SYSTEM VIEW |
+-------------+
1 row in set (0.001 sec)
mysql> CALL sys.table_exists(''db1'', ''t3'', @exists); SELECT @exists;
Query OK, 0 rows affected (0.01 sec)
+---------+
| @exists |
+---------+
| |
+---------+
1 row in set (0.00 sec)
'
SQL SECURITY INVOKER
NOT DETERMINISTIC
CONTAINS SQL
BEGIN
DECLARE v_error BOOLEAN DEFAULT FALSE;
DECLARE db_quoted VARCHAR(64);
DECLARE table_quoted VARCHAR(64);
DECLARE v_table_type VARCHAR(16) DEFAULT '';
DECLARE v_system_db BOOLEAN
DEFAULT LOWER(in_db) IN ('information_schema', 'performance_schema');
DECLARE CONTINUE HANDLER FOR 1050 SET v_error = TRUE;
DECLARE CONTINUE HANDLER FOR 1146 SET v_error = TRUE;
SET out_exists = '';
SET db_quoted = sys.quote_identifier(in_db);
SET table_quoted = sys.quote_identifier(in_table);
-- Verify whether the table name exists as a normal table
IF (EXISTS(SELECT 1 FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table)) THEN
-- Unfortunately the only way to determine whether there is also a temporary table is to try to create
-- a temporary table with the same name. If it succeeds the table didn't exist as a temporary table.
IF v_system_db = FALSE THEN
SET @sys.tmp.table_exists.SQL = CONCAT('CREATE TEMPORARY TABLE ',
db_quoted,
'.',
table_quoted,
'(id INT PRIMARY KEY)');
PREPARE stmt_create_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_create_table;
DEALLOCATE PREPARE stmt_create_table;
-- The temporary table was created, i.e. it didn't exist. Remove it again so we don't leave garbage around.
SET @sys.tmp.table_exists.SQL = CONCAT('DROP TEMPORARY TABLE ',
db_quoted,
'.',
table_quoted);
PREPARE stmt_drop_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_drop_table;
DEALLOCATE PREPARE stmt_drop_table;
END IF;
IF (v_error) THEN
SET out_exists = 'TEMPORARY';
ELSE
SET v_table_type = (SELECT TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table);
-- Don't fail on table_type='SYSTEM VERSIONED'
-- but return 'BASE TABLE' for compatibility with existing tooling
IF v_table_type = 'SYSTEM VERSIONED' THEN
SET out_exists = 'BASE TABLE';
ELSE
SET out_exists = v_table_type;
END IF;
END IF;
ELSE
-- Check whether a temporary table exists with the same name.
-- If it does it's possible to SELECT from the table without causing an error.
-- If it does not exist even a PREPARE using the table will fail.
IF v_system_db = FALSE THEN
SET @sys.tmp.table_exists.SQL = CONCAT('SELECT COUNT(*) FROM ',
db_quoted,
'.',
table_quoted);
PREPARE stmt_select FROM @sys.tmp.table_exists.SQL;
IF (NOT v_error) THEN
DEALLOCATE PREPARE stmt_select;
SET out_exists = 'TEMPORARY';
END IF;
END IF;
END IF;
END$$
DELIMITER ;
|
