别名在查询中不起作用

Question

我需要显示提出最大查询次数的用户及其部门的名称。我通过加入5个表格来编写以下查询; user,query,profile,degree和department。

问题在于结果别名未被用于列名称。对于这两种列看起来像刚才name

select user.name 'USER_NAME',department.name 'DEPT_NAME' 
from user 
inner join query on (query.user_id=user.id) 
inner join profile on (user.profile_id=profile.id) 
inner join degree on (profile.degree_id=degree.id) 
inner join department on (degree.department_id=department.id) 
group by user.name 
order by count(query.id) desc 
limit 1 

Answer 1

使用“为”关键字，以便在MySQL中使用别名，并删除单引号。

select user.name as USER_NAME from user; 

Answer 2

以下语法工作完美的我：

select U.name AS "USER_NAME", D.name AS "DEPT_NAME" 
from user U 
inner join query Q on (Q.user_id=U.id) 
inner join profile P on (U.profile_id=P.id) 
inner join degree C on (P.degree_id=C.id) 
inner join department D on (C.department_id=D.id) 
group by U.name 
order by count(Q.id) desc 
limit 1; 

有时候，Mysql的喜欢你板着脸对你列一个别名，当您使用一些JOIN。

Answer 3

试试吧，

select thisuser.name 'USER_NAME',department.name 'DEPT_NAME' 
from user as thisuser 
inner join query on (query.user_id=thisuser.id) 
inner join profile on (thisuser.profile_id=profile.id) 
inner join degree on (profile.degree_id=degree.id) 
inner join department on (degree.department_id=department.id) 
group by thisuser.name 
order by count(query.id) desc 
limit 1 

但是在构建查询时这不是一个好的做法; 它看起来像这样

select thisuser.name,thisdept.name from 
(select name,user_id from user) as thisuser 
inner join 
(select name,user_id from department) as thisdept 
on thisuser.user_id = thisdept.user_id 

Answer 4

只需删除从您的查询报价，它会工作，但你可以使用关键字AS要清楚，你正在使用的别名。

我还要为了避免与关键字的混乱，同时也使用大写关键字使用小写的别名;

SELECT user.name AS user_name, department.name AS dept_name 
...