MySQL存储过程相互调用并获得错误码

mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc()
    ->      MODIFIES SQL DATA
    -> BEGIN
    ->      DECLARE l_status VARCHAR(20);
    ->
    ->     CALL myProc1(l_status);
    ->        IF l_status='Duplicate Entry' THEN
    ->               SELECT CONCAT('Warning: using existing definition for location ') AS warning;
    ->      END IF;
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> CREATE PROCEDURE myProc1(OUT out_status VARCHAR(30))
    -> BEGIN
    ->    set out_status = 'Duplicate Entry';
    -> END$$
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql>
mysql> delimiter ;
mysql> call myProc();
+--------------------------------------------------+
| warning                                          |
+--------------------------------------------------+
| Warning: using existing definition for location  |
+--------------------------------------------------+
1 row in set (0.00 sec)

Query OK, 0 rows affected (0.01 sec)

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

mysql> drop procedure myProc1;
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql>