如何在 MySQL 中使用 group by 和 pivot？

Question

任何人都可以帮我分组 2 tables 并显示如下...

我的第一个 table 是：

user_id |部
----------------------
1 |用户1
----------------------
2 |用户2
----------------------

和 table 2 是：

reserve_id | user_id | reserve_status
--------------------------------------
    1 | 1 | 1个
--------------------------------------
    2 | 1 | 1个
--------------------------------------
    3 | 1 | 2个
--------------------------------------
    4 | 2 | 2个
--------------------------------------
    5 | 2 | 0
--------------------------------------
    6 | 2 | 1个

*reserve_status 0 取消选中，1 = 批准，2 = 不批准

我想要这样的产品：

部门|总和储备 | sumreservapprove | sumreserveunapprove |取消勾选
---------------------------------------------- --------------------------
 用户1 | 3 | 2 | 1 | 0
---------------------------------------------- --------------------------
 用户2 | 3 | 1 | 1 | 1个

抱歉英语不好

Answer 1

您需要一个枢纽解决方案。

演示:
假设 so_q27895250_users 和 so_q27895250_reserve 作为 table 名称

mysql>
mysql> select u.department, count(r.reserve_status) as total_reserves,
    ->     count( case when r.reserve_status = 0
    ->                         then r.reserve_status else null end ) as unchecked,
    ->     count( case when r.reserve_status = 1
    ->                         then r.reserve_status else null end ) as approved,
    ->     count( case when r.reserve_status = 2
    ->                         then r.reserve_status else null end ) as unapproved
    ->   from so_q27895250_reserve r
    ->     left join so_q27895250_users u
    ->                    on r.user_id = u.user_id
    ->  group by r.user_id
    -> ;
+------------+----------------+-----------+----------+------------+
| department | total_reserves | unchecked | approved | unapproved |
+------------+----------------+-----------+----------+------------+
| user1      |              3 |         0 |        2 |          1 |
| user2      |              3 |         1 |        1 |          1 |
+------------+----------------+-----------+----------+------------+
2 rows in set (0.00 sec)

如何在 MySQL 中使用 group by 和 pivot？

How to use group by with pivot in MySQL?

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