这是查询: SELECT a.id, a.userName,if(o.userId=1,'C',if(i.userId=1,'I','N')) AS relation
FROM tbl_users AS a
LEFT JOIN tbl_contacts AS o ON a.id = o.contactId
LEFT JOIN tbl_invites AS i O
所有行我愿做一个具体的查询 select distinct name
from tablename
删除重复。但是这只给了我名字。从“选择表不同的名字:”我想所有的列有一个WHERE条件返回: select *
from tablename
where value= 1
我尝试这样做: select *
from tablename
where value = 1 and exi