查詢鏈接表SQL

Question

我在繞過簡單查詢時遇到了問題。我有一個Link表是這樣的：

+----------+----------+ 
| SourceID | TargetID | 
+----------+----------+ 
| 1  | 2  | 
+----------+----------+ 
| 1  | 3  | 
+----------+----------+ 
| 3  | 4  | 
+----------+----------+ 
| 3  | 5  | 
+----------+----------+ 

和Names

+----------+----------+ 
| ID  | Name  | 
+----------+----------+ 
| 1  | Mitch | 
+----------+----------+ 
| 2  | Cheryl | 
+----------+----------+ 
| 3  | Sue  | 
+----------+----------+ 
| 4  | Harry | 
+----------+----------+ 
| 5  | Bob  | 
+----------+----------+ 

一個表，我希望輸出像這樣。像鏈接表一樣結構化，但用名稱代替。

+------------+------------+ 
| SourceName | TargetName | 
+------------+------------+ 
| Mitch  | Cheryl  | 
+------------+------------+ 
| Mitch  | Sue  | 
+------------+------------+ 
| Sue  | Harry  | 
+------------+------------+ 
| Sue  | Bob  | 
+------------+------------+ 

感謝您的幫助。

Answer 1

您必須joinnames表使用不同的別名兩次。如果link表的ID不在names中，請將join更改爲left join。

Fiddle

select t1.name as sourcename, t3.name as targetname 
from link t2 
join names t1 on t1.id = t2.sourceid 
join names t3 on t3.id = t2.targetid