问题
If I create a stored procedure in MySQL with an OUT or INOUT parameter, it does not work. Even if I leave the stored procedure empty. The DDL is as follows:
CREATE DEFINER=`root`@`localhost` PROCEDURE `testing_inout`(`a` int,INOUT `b` int)
BEGIN
END
The first parameter is a regular IN parameter. The second one is an INOUT paremeter (even if set as OUT the same problem persists)
When I call this stored procedure, I get an error stating:
OUT or INOUT argument 2 for routine db_name.testing_inout is not a variable or NEW pseudo-variable in BEFORE trigger.
This error persists even if code is written inside the stored procedure. I am running mysql version 5.1.41.
This is a big problem for me because I cannot output the result of a recursive stored procedure because of this error.
回答1:
it works for me
mysql> CREATE DEFINER=`root`@`localhost` PROCEDURE `testing_inout`(`a` int,INOUT `b` int)
-> BEGIN
->
-> END
-> ;
Query OK, 0 rows affected (0.00 sec)
The second parameter because it's inout it need to be a variable:
mysql> set @c:=1;
Query OK, 0 rows affected (0.00 sec)
mysql> call testing_inout(1,@c);
Query OK, 0 rows affected (0.00 sec)
if you try this it will return 1:
delimiter |
CREATE DEFINER=`root`@`localhost` PROCEDURE `testing_inout`(`a` int,INOUT `b` int)
BEGIN
select b;
END
|
delimiter ;
mysql> call testing_inout(1,@c);
+------+
| b |
+------+
| 1 |
+------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.00 sec)
来源：https://stackoverflow.com/questions/11267868/out-or-inout-parameter-not-working