MySQL 如何创建带有INOUT参数的MySQL存储过程？

下面的示例将演示带有 INOUT 参数的MySQL存储过程 –

mysql> DELIMITER //;
mysql> Create PROCEDURE counter(INOUT count INT, IN increment INT)
    -> BEGIN
    -> SET count = count + increment;
    -> END //
Query OK, 0 rows affected (0.03 sec)

这里，’count’是INOUT参数，它可以存储和返回值；’increment’是IN参数，它接受用户输入的值。

mysql> DELIMITER ;
mysql> SET @counter = 0;
Query OK, 0 rows affected (0.00 sec)

mysql> CALL counter(@Counter, 1);
Query OK, 0 rows affected (0.00 sec)

mysql> Select @Counter;
+----------+
| @Counter |
+----------+
| 1        |
+----------+
1 row in set (0.00 sec)

mysql> CALL counter(@Counter, 5);
Query OK, 0 rows affected (0.00 sec)

mysql> Select @Counter;
+----------+
| @Counter |
+----------+
| 6        |
+----------+
1 row in set (0.00 sec)

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