MySQL:如果字段为空,则赋值

Question

这是我的查询:

$sql = "SELECT u.PHONE , u.STATE , if (uo.CHANNEL='','web',channel) as TYPE FROM user
LEFT JOIN user_oferts uo ON u.PHONE=uo.PHE_USER 
WHERE (u.STATE='active') ";

它工作得很好,我得到了我想要的但是空的频道.

如果它不是"wap",我需要频道为"web",这样频道不会为空或空或无.我怎样才能做到这一点？我究竟做错了什么？

非常感谢

Answer 1

select 
...
case when channel = '' then 
   web 
else 
   channel 
end as TYPE....

使用CASE语句.

即为你的情况

$sql = "SELECT u.PHONE , u.STATE 
, case when coalesce(uo.CHANNEL, '') = '' then 'web' else channel end as TYPE 
FROM user
LEFT JOIN user_oferts uo ON u.PHONE=uo.PHE_USER 
WHERE (u.STATE='active') ";

编辑:添加coalesce以处理可能的NULL值.