表中的多个外键引用相同的主键另一个表 [英] Multiple foreign keys in a table referencing the same primary key another table

问题描述

我遇到了表中多个外键的要求

引用相同的主键另一个表。

表结构如下：

表名

i came across requirement of multiple foreign keys in a table
referencing the same primary key another table.
Table structure is as follows:
Table Name

引用：

File_Master

File_Master

file_id

file_no

from_Designation_id

to_Designation_id



表名

file_id
file_no
from_Designation_id
to_Designation_id

Table Name

引用：

Designation_Master

Designation_Master

Designation_id

Designation_name



File_Master有多个外国人密钥（from_Designation_id，to_Designation_id），参考Designation_Master Designation_id（pk）。



现在任何人都可以帮我加入以上两个表格如下

file_id，file_no，from_Designation，to_Designation

Designation_id
Designation_name

File_Master has multiple foreign keys(from_Designation_id,to_Designation_id) which reference Designation_Master Designation_id(pk) .

Now can anyone please help me to join these above two table as follows
file_id, file_no, from_Designation, to_Designation

推荐答案

尝试

Try

SELECT file_id, file_no, DM1.Designation_name AS from_Designation, DM2.Designation_name AS to_Designation
FROM File_Master F
LEFT JOIN Designation_Master DM1 ON F.from_Designation_id = DM1.Designation_id
LEFT JOIN Designation_Master DM2 ON F.to_Designation_id = DM2.Designation_id

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