如何在存储过程中使用IF并在MySQL中选择？
您可以在存储过程和IF()select语句中使用IF。
选择语句中的IF()
IF() in select statement mysql> select if(0=0,'Hello MySQL','condition is wrong');
这将产生以下输出-
+------------------------------------------------------+
| if('test'='test','Hello MySQL','condition is wrong') |
+------------------------------------------------------+
| Hello MySQL |
+------------------------------------------------------+
1 row in set (0.00 sec)第二种情况，如果您的条件出错-
mysql> select if(1=0,'Hello MySQL','condition is wrong');
这将产生以下输出-
+--------------------------------------------+ | if(1=0,'Hello MySQL','condition is wrong') | +--------------------------------------------+ | condition is wrong | +--------------------------------------------+ 1 row in set (0.00 sec)
如果在存储过程中
创建存储过程的查询如下。在这里，我们使用IF设置条件-
mysql> DELIMITER //
mysql> CREATE PROCEDURE if_demo(value int)
BEGIN
IF 1=value
THEN SELECT "Hello MySQL";
ELSE
SELECT "Wrong Condition";
END IF;
END
//
mysql> DELIMITER ;现在，您可以使用call命令来调用存储过程。
mysql> call if_demo(1);
这将产生以下输出-
+-------------+ | Hello MySQL | +-------------+ | Hello MySQL | +-------------+ 1 row in set (0.00 sec)
如果您的条件为假-
mysql> call if_demo(0);
这将产生以下输出-
+-----------------+ | Wrong Condition | +-----------------+ | Wrong Condition | +-----------------+ 1 row in set (0.00 sec)