OUT或INOUT参数不起作用

问题描述

如果我在MySQL中使用OUT或INOUT参数创建存储过程，它将无法正常工作.即使我将存储过程留空. DDL如下:

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

第一个参数是常规IN参数.第二个是INOUT参数(即使设置为OUT，同样的问题仍然存在)

The first parameter is a regular IN parameter. The second one is an INOUT paremeter (even if set as OUT the same problem persists)

当我调用此存储过程时，出现错误提示:

When I call this stored procedure, I get an error stating:

即使在存储过程中编写了代码，该错误仍然存​​在.我正在运行mysql版本5.1.41.

This error persists even if code is written inside the stored procedure. I am running mysql version 5.1.41.

这对我来说是个大问题，因为由于这个错误，我无法输出递归存储过程的结果.

This is a big problem for me because I cannot output the result of a recursive stored procedure because of this error.

推荐答案

对我有用

mysql> CREATE DEFINER=`root`@`localhost` PROCEDURE `testing_inout`(`a` int,INOUT `b` int)
    -> BEGIN
    -> 
    -> END
    -> ;
Query OK, 0 rows affected (0.00 sec)

第二个参数，因为它是inout，它需要是一个变量:

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)

如果尝试此操作，它将返回1:

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)

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