MySQL的使用相同的表連接，而不重複

Question

我有一個表instructors有以下謝靈運/數據：

----------------- 
|id | name  | 
----------------- 
|1 | saad  | 
|2 | imran | 
----------------- 

我想要做一個不返回重複的結果與同桌一起。

如果我做了一個簡單的連接，查詢返回4行[saad, saad], [saad, imran], [imran, imran], [imran, saad]。

如果我添加一個where子句，它返回2行[saad, imran], [imran, saad]。

但是，我只想返回1行，（即如果[saad, imran]已經返回，查詢不應該返回[imran, saad]）。

這裏是我的查詢迄今：

SELECT DISTINCT 
    i1.name AS name1, 
    i2.name AS name2 
FROM 
    instructors i1, instructors i2 
WHERE 
    i1.name != i2.name 
ORDER BY 
    name1, name2 

Answer 1

試試這個：

SELECT DISTINCT 
    i1.name AS name1, 
    i2.name AS name2 
FROM 
    instructors i1, instructors i2 
WHERE 
    i1.id < i2.id 
ORDER BY 
    name1, name2 

Answer 2

嘗試：

SELECT DISTINCT 
    i1.name AS name1, 
    i2.name AS name2 
FROM 
    instructors i1, instructors i2 
WHERE 
    i1.name > i2.name 
ORDER BY 
    name1, name2