sql - SQL Server：根据指向单个表的 id 选择数据

Question

我正在尝试基于两个表创建一个视图。

成员：

ID  Lang1_ID  Lang2_ID - all tinyint
1   2         3
2   2         4
3   1         4

语言：

ID  Title - tinyint, varchar(50)
1   English
2   French
3   Spanish
4   Portuguese

我希望创建一个包含所有标题的视图：

member_id, Lang1_Title, Lang2_Title

需要的结果：

1  French  Spanish
2  French  Portuguese
3  English Portuguese

Answer 1

SELECT m.id member_id, l.Title Lang1_Title, l2.Title Lang2_Title
  FROM Member m LEFT JOIN 
       Language l ON m.Lang1_ID = l.ID LEFT JOIN
       Language l2 ON m.Lang2_ID = l2.ID

输出

| MEMBER_ID | LANG1_TITLE | LANG2_TITLE |
-----------------------------------------
|         1 |      French |     Spanish |
|         2 |      French |  Portuguese |
|         3 |     English |  Portuguese |

sqlfiddle 示例

和视图

CREATE VIEW viewname
AS
SELECT m.id member_id, l.Title Lang1_Title, l2.Title Lang2_Title
  FROM Member m LEFT JOIN 
       Language l ON m.Lang1_ID = l.ID LEFT JOIN
       Language l2 ON m.Lang2_ID = l2.ID

并使用它

SELECT * FROM viewname

sqlfiddle 示例