MYSQL：如何在引用同一個表的同一個查詢上連接兩個表兩次

Question

我有兩個表。我試圖加入下面的示例兩個表格，並將表格兩次引用表格2兩次。例如，如果我看錶1：組2和構件7，但應查找的ID在表2中，並給我的輸出：

Group Members Name Name 
    2  7  Blue Dog 

表1

Group Members 
2  7 
3  8 
5  10 

表2

ID  Name 
1  Green 
2  Blue 
3  Yellow 
4  Orange 
5  Red 
6  Elephant 
7  Dog 
8  Cat 
9  Chicken 
10  Mouse 

有什麼建議嗎？謝謝

Answer 1

SELECT 
    Table_1.*, 
    g.Name, 
    m.Name 
FROM 
    Table_1 
    INNER JOIN Table_2 AS g ON Table_1.Group=g.ID 
    INNER JOIN Table_2 AS m ON Table_1.Group=m.ID 
WHERE 
    Table_1.Group=2 
    AND Table_1.Member=7 

Answer 2

在不同的列上連接兩次表2。

SELECT t1.*, t2.name AS group_name, t3.name AS member_name 
FROM Table1 AS t1 
JOIN Table2 AS t2 ON t1.group = t2.id 
JOIN Table2 AS t3 ON t1.members = t3.id 

Answer 3

很難準確地告訴您需要從該描述中得到什麼，但表格可能是您需要的。它的工作原理是這樣的：

SELECT t1.x, t2_1.y, t2_2.z 
FROM table1 AS t1 
JOIN table2 AS t2_1 ON t1.whatever = t2_1.whatever 
JOIN table2 AS t2_2 ON t1.whatever = t2_2.whatever 
...