如何在MySQL查询中编写IF ELSE语句

Question

如何在MySQL查询中编写IF ELSE语句？像这样：mysql_query("...(irrelevant code).. IF(action==2&&state==0){state=1}");然后在我的数组中，我应该能够做到这一点： $row['state'] //this should equal 1, the query should not change anything in the database, //just the variable for returning the information

Answer 1

您可能要使用CASE表达式。

他们看起来像这样：

SELECT col1, col2, (case when (action = 2 and state = 0) 

 THEN

      1 

 ELSE

      0 

 END)

Answer 2

您必须使用SQL而不是C / PHP样式编写它

IF( action = 2 AND state = 0, 1, 0 ) AS state

用于查询

IF ( action = 2 AND state = 0 ) THEN SET state = 1

用于存储过程或函数