Re: Does Table Exist
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I Like the solution that AWS has for it (as a SP in the SYS schema called "table_exists")
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CREATE PROCEDURE sys.table_exists(IN in_db VARCHAR(64), IN in_table VARCHAR(64), OUT out_exists ENUM('', 'BASE TABLE', 'VIEW', 'TEMPORARY') )
SQL SECURITY INVOKER
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 existance of the table in.
in_table (VARCHAR(64)):
The name of the table to check the existance 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, 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.
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)
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)
'
BEGIN
DECLARE v_error BOOLEAN DEFAULT FALSE;
DECLARE CONTINUE HANDLER FOR 1050
SET v_error = TRUE;
DECLARE CONTINUE HANDLER FOR 1146
SET v_error = TRUE;
SET out_exists = '';
IF (EXISTS(SELECT 1 FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table)) THEN
SET @sys.tmp.table_exists.SQL = CONCAT('CREATE TEMPORARY TABLE `', in_db, '`.`', in_table, '` (id INT PRIMARY KEY)');
PREPARE stmt_create_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_create_table;
DEALLOCATE PREPARE stmt_create_table;
IF (v_error) THEN
SET out_exists = 'TEMPORARY';
ELSE
SET @sys.tmp.table_exists.SQL = CONCAT('DROP TEMPORARY TABLE `', in_db, '`.`', in_table, '`');
PREPARE stmt_drop_table FROM @sys.tmp.table_exists.SQL;
EXECUTE stmt_drop_table;
DEALLOCATE PREPARE stmt_drop_table;
SET out_exists = (SELECT TABLE_TYPE FROM information_schema.TABLES WHERE TABLE_SCHEMA = in_db AND TABLE_NAME = in_table);
END IF;
ELSE
SET @sys.tmp.table_exists.SQL = CONCAT('SELECT COUNT(*) FROM `', in_db, '`.`', in_table, '`');
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