許多由relantionship

Question

很多爲了我有以下表格：

+---------+ +-----------+  +---------+ 
| USER | | USER_BOX |  | BOX  | 
| id  | | user_id |  | id  | 
| name | | box_id |  | name | 
|   | |   |  |   | 
+---------+ +-----------+  +---------+ 

我想要做的就是查詢數據庫，以列出所有箱子，但必須有與用戶關係的所有盒上市第一次，只有一次。我卡住了，我甚至不確定MySql支持這樣的查詢。

 USER     BOX     USER_BOX 
+--------|--------+  +--------|--------+ +--------|--------+ 
| 0 | Jonh |  | 0 | Boobox | | 0 | 4 | 
+--------|--------+  | 1 | RedBox | | 0 | 3 | 
         | 2 | GGbox | +--------|--------+ 
         | 3 | OKbox | 
         | 4 | boxy | 
         +--------|--------+ 

結果查詢將返回：

4 - boxy 
3 - Okbox 
0 - Boobox  
1 - RedBox 
2 - GGbox 

編輯：我們的想法是能夠通過用戶查詢，所以它更容易找到在一個大的列表中的用戶框。

Answer 1

SELECT b.id, b.name 
FROM BOX b 
LEFT JOIN (
    USER_BOX ub 
    JOIN USER u ON (user_id = u.id) 
) ON (box_id = b.id) 
ORDER BY 
    u.id IS NULL, 
    b.id DESC 

http://sqlfiddle.com/#!2/a4f304/4/0

編輯：其實沒有必要加入對USER。
http://sqlfiddle.com/#!2/a4f304/7/0

Answer 2

事情是這樣的：

SELECT a.id, a.name 
FROM BOX AS a 
LEFT JOIN USER_BOX AS b 
ON a.id = b.box_id 
ORDER BY CASE WHEN b.box_id IS NOT NULL THEN 0 ELSE 1 END 
     ,a.id 

Answer 3

SELECT * FROM BOX 
WHERE box_id IN (SELECT box_id FROM USER_BOX) 
UNION ALL 
SELECT * FROM BOX 
WHERE box_id NOT IN (SELECT box_id FROM USER_BOX)