如果条件里面MySQL查询

Question

我需要给条件MySQL查询里面，

select IF(r.name=NULL,'customer',r.name) as previlage 
from users u LEFT JOIN role r on r.rid = u.uid ORDER BY u.created DESC\G 

我需要检查if the r.name field is null then it should be displayed as customer，但现在if r.name is NULL then its displayed as null itself。我怎样才能做到这一点，谢谢。

Answer 1

你不能=比较NULL，你需要使用is null

r.name is null 

，而不是

r.name=NULL 

https://dev.mysql.com/doc/refman/5.0/en/working-with-null.html