Question

我有以下表格

[users]
id BIGINT,
name VARCHAR(255),
email VARCHAR(255),
role ENUM('admin', 'executive', 'pos')
...

[transactions]
id BIGINT
fname VARCHAR(255),
lname VARCHAR(255),
mobile CHAR(10),
email VARCHAR(255),
amount FLOAT(7, 2),
verified_by BIGINT NOT NULL        # Refers to user.id
...

[refunds]
id BIGINT
transaction_id BIGINT,
amount FLOAT(7,2)
initiated_by BIGINT NOT NULL,      # Refers to user.id
processed_by BIGINT NULL           # Refers to user.id
...

我想加入退款表，以便显示交易信息以及refunds.initiated_by和refunds.processed_by的users.name。由于退款是由具有角色pos的用户发起的，后来由具有角色执行的其他用户处理。我不想将用户表分成用户，主管和pos，除了角色，所有其他字段对于这三个都是相同的。

目前，我可以获取交易信息以及发起退款的用户的姓名。

SELECT refunds.id, fname, lname, mobile, transactions.email,
       transactions.amount AS transaction_amount, refunds.amount AS refund_amount,
       users.name AS initiated_by, refunds.processed_by
FROM refunds 
JOIN transactions
    ON refunds.transaction_id=transactions.id 
JOIN users
    ON users.id=refunds.initiated_by;

这给了我除了处理退款的用户名之外的所有内容。我怎么做到的？

提前致谢！

Answer 1

我认为您可以再次加入users表格，以引入处理退款的用户名称：

SELECT r.id,
       t.fname,
       t.lname,
       t.mobile,
       t.email,
       t.amount AS transaction_amount,
       r.amount AS refund_amount,
       u1.name AS initiated_by,
       u2.name AS processed_by,
       r.processed_by
FROM refunds r
INNER JOIN transactions t
    ON r.transaction_id = t.id 
INNER JOIN users u1
    ON u1.id = r.initiated_by
INNER JOIN users u2
    ON u2.id = r.processed_by

加入三个具有相同列的表

1 个答案: