mysql表有两个来自另一个表的外键

Question

我有两张桌子。

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1. 发票
2. 用户

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在用户表中我有

user_id
user_name
user_email    
user_address

在发票表中我有

invoice_id
invoice_to_user_id
invoice_by_user_id
invoice_date

在发票表中，我有两个来自用户表的外键 invoice_to_user_id
2. invoice_by_user_id

现在我想进行单一查询，获取两个外键的用户信息.g。，
1. invoice_to_user_name
2. invoice_to_user_email
3. invoice_to_user_address
4. invoice_by_user_name
5. invoice_by_user_email
6. invoice_by_user_address

提前致谢。

Answer 1

SELECT t.user_name    AS invoice_to_user_name,
       t.user_email   AS invoice_to_user_email,
       t.user_address AS invoice_to_user_address,
       b.user_name    AS invoice_by_user_name,
       b.user_email   AS invoice_by_user_email,
       b.user_address AS invoice_by_user_address
FROM invoice i
LEFT JOIN user t ON t.user_id = i.invoice_to_user_id
LEFT JOIN user b ON b.user_id = i.invoice_by_user_id

Answer 2

将发票表与用户表连接两次，一次在invoice_to_user_id上，然后再次在invoice_by_user_id上，例如

SELECT
INV.invoice_id,
US1.user_name AS invoice_to_user_name,
US1.user_email AS invoice_to_user_email,
US1.user_address AS invoice_to_user_address,
US2.user_name AS invoice_by_user_name,
US2.user_email AS invoice_by_user_email,
US2.user_address AS invoice_by_user_address
FROM
[invoice] INV
INNER JOIN [user] US1 ON INV.invoice_to_user_id = US1.user_id
INNER JOIN [user] US2 ON INV.invoice_by_user_id = US2.user_id