如何实现两个表左连接的Mysql Union

Question

有存款表

然后有提款表

我必须创建一个 mysql 查询，以便我有列 用户 ID、姓名、电子邮件、总存款、总提款和净额（总存款 - 总提款） 对于上面两个表中的给定日期范围 状态为已批准 根据网络订购

对于某个用户id，提款表中有记录，但充值表没有记录，则相应期间的提款总额为0 反之亦然 如果某个用户 ID 的存款表中有记录，但提款表中没有记录，那么对于此类用户，相应期间的提款总额为 0

如何用MYSQL查询实现这一点

Answer 1

首先，准备一个数据集，该数据集是两个表的并集，但仅包含“已批准”记录：

SELECT *, 'deposit' AS type FROM deposit WHERE status = 'Approved'
UNION ALL
SELECT *, 'widthdraw' AS type FROM withdraw WHERE status = 'Approved'

然后您可以从该数据集中进行选择，并带有一些条件总和：

WITH alltypes AS (
    SELECT *, 'deposit' AS type FROM deposit WHERE status = 'Approved'
    UNION ALL
    SELECT *, 'widthdraw' AS type FROM withdraw WHERE status = 'Approved'
)
SELECT
    userid,
    name,
    email,
    SUM(if(type = 'deposit', amount, 0)) AS 'total deposit',
    SUM(if(type = 'withdraw', amount, 0)) AS 'total withdraw',
    SUM(if(type = 'deposit', amount, -1 * amount)) AS 'net'
FROM alltypes
GROUP BY userid, name, email

这给出：

+--------+------+---------------+---------------+----------------+------+
| userid | name | email         | total deposit | total withdraw | net  |
+--------+------+---------------+---------------+----------------+------+
|      1 | fine | [email protected] |           500 |              0 |  450 |
|      4 | new  | [email protected]   |            20 |              0 |  -10 |
+--------+------+---------------+---------------+----------------+------+