Using Set to declare variable in a procedure : Set « Procedure Function « MySQL Tutorial

1. MySQL Tutorial
2. Procedure Function
3. Set

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE execute_immediate(in_sql varchar(4000))
    -> BEGIN
    ->
    ->   SET @tmp_sql=in_sql;
    ->   PREPARE s1 FROM @tmp_sql;
    ->   EXECUTE s1;
    ->   DEALLOCATE PREPARE s1;
    ->
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> delimiter ;
mysql> call execute_immediate("select 1+1");
+-----+
| 1+1 |
+-----+
|   2 |
+-----+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.02 sec)

mysql> drop procedure execute_immediate;
Query OK, 0 rows affected (0.00 sec)