Use dynamic SQL in mysql

Mysql> set @ SQL _text: = 'select count (*) from test ';
Query OK, 0 rows affected (0.00 sec)

Mysql> prepare stmt from @ SQL _text;
Query OK, 0 rows affected (0.04 sec)
Statement prepared

Mysql> execute stmt;
+ ---------- +
| Count (*) |
+ ---------- +
| 0 |
+ ---------- +
1 row in set (0.19 sec)

Mysql> deallocate prepare stmt;
Query OK, 0 rows affected (0.00 sec)

Changing the value of @ SQL _text In the stored procedure can achieve the dynamic SQL effect.

Note that SQL statements that can use prepare have restrictions:

The following SQL statements can be used in prepared statements: CREATE TABLE, DELETE, DO, INSERT, REPLACE, SELECT, SET, UPDATE, and most SHOW statements. supported. analyze table, optimize table, and repair table are supported as of MySQL 5.0.23. other statements are not yet supported.