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