我應該怎樣改變我的sql語句，以便我可以用這張表來到達？

Question

你好我堅持這個問題，我有表

投訴：

Complaint table

用戶：

User table

，我想提取是在用戶投訴具體省

例如：如果我想提取伊羅戈省的投訴，我的表是這樣的

complaint_id | user_id | complaint_title| complaint_category | complaint_desc 
--------------------------------------------------------------------------------- 
17   | 2  | 2    | Accidents   | qwe123 

IVE帶着這條SQL語句：

SELECT DISTINCT complaint.complaint_id, complaint.user_id, 
     complaint.complaint_title,complaint.complaint_desc       
FROM complaint LEFT JOIN 
    user 
    ON user.province = 'ILOCOS' LEFT JOIN 
    complaint_media 
    ON complaint.complaint_id = complaint_media.complaint_id 

Answer 1

你需要加入投訴表與用戶表在user_id列上，否則它將是笛卡爾連接。

select distinct complaint.complaint_id, -- check if you really need "DISTINCT" 
    complaint.user_id, 
    complaint.complaint_title, 
    complaint.complaint_desc, 
    . . . 
from complaint 
join user 
    on complaint.user_id = user.user_id  -- here 
     and user.province = 'ILOCOS' 
join complaint_media 
    on complaint.complaint_id = complaint_media.complaint_id