別名在查詢中不起作用

Question

我需要顯示提出最大查詢次數的用戶及其部門的名稱。我通過加入5個表格來編寫以下查詢; user,query,profile,degree和department。

問題在於結果別名未被用於列名稱。對於這兩種列看起來像剛纔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「爲」關鍵字，以便在MySQL中使用別名，並刪除單引號。

select user.name as USER_NAME from user; 

Answer 2

以下語法工作完美的我：

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; 

有時候，Mysql的喜歡你板着臉對你列一個別名，當您使用一些JOIN。

Answer 3

試試吧，

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 

但是在構建查詢時這不是一個好的做法; 它看起來像這樣

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

只需刪除從您的查詢報價，它會工作，但你可以使用關鍵字AS要清楚，你正在使用的別名。

我還要爲了避免與關鍵字的混亂，同時也使用大寫關鍵字使用小寫的別名;

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