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)