我有位置表
tbl_positions
id position
1 Driver
2 Lobby
3 Support
4 Constructor
在其他表中我有用户
编辑:
tbl_workers
id name position position2 status
1 John 2 3 4
2 Mike 3 2 2
3 Kate 2 0 3
4 Andy 1 0 0
我确实要求职位
SELECT p.id,
p.position,
SUM(CASE w.Status WHEN 2 THEN 1 ELSE 0 END) AS booked,
SUM(CASE w.Status WHEN 3 THEN 1 ELSE 0 END) AS placed
FROM tbl_positions AS p LEFT JOIN tbl_workers AS w
ON w.position=p.id
GROUP BY p.id, p.position
我在单个查询中需要这样的输出。
Position booked placed
Driver 0 0
Lobby 1 2
Support 0 2
Constructor 0 0
我需要评估字段 positon1 和 position2 而不是一个。我认为修改它很容易,但我找不到合适的解决方案,请帮忙。
编辑:添加状态 4
最佳答案
除了加入 tbl_workers
,您还可以加入它的非透视变体,其中 position
和 position2
将在同一列但在不同的行中.
这是逆透视的样子:
SELECT
w.id,
w.name,
CASE x.pos WHEN 1 THEN w.position ELSE w.position2 END AS position,
w.status
FROM tbl_workers AS w
CROSS JOIN (SELECT 1 AS pos UNION ALL SELECT 2) AS x
这是整个查询,基本上是用上面的查询替换 tbl_workers
表的原始查询:
SELECT p.id,
p.position,
SUM(CASE w.Status WHEN 2 THEN 1 ELSE 0 END) AS booked,
SUM(CASE w.Status WHEN 3 THEN 1 ELSE 0 END) AS placed
FROM tbl_positions AS p
LEFT JOIN (
SELECT
w.id,
w.name,
CASE x.pos WHEN 1 THEN w.position ELSE w.position2 END AS position,
w.status
FROM tbl_workers AS w
CROSS JOIN (SELECT 1 AS pos UNION ALL SELECT 2) AS x
) AS w
ON w.position=p.id
GROUP BY p.id, p.position
更新
这是根据评论中的额外要求修改的脚本:
SELECT p.id,
p.position,
SUM(CASE w.Status WHEN 2 THEN 1 ELSE 0 END) AS booked,
SUM(CASE w.Status WHEN 3 THEN 1 ELSE 0 END) AS placed
FROM tbl_positions AS p
LEFT JOIN (
SELECT
w.id,
w.name,
CASE x.pos WHEN 1 THEN w.position ELSE w.position2 END AS position,
CASE w.status
WHEN 4 THEN CASE x.pos WHEN 1 THEN 3 ELSE 2 END
ELSE w.status
END AS status
FROM tbl_workers AS w
CROSS JOIN (SELECT 1 AS pos UNION ALL SELECT 2) AS x
) AS w
ON w.position=p.id
GROUP BY p.id, p.position
想法是用 3
或 2
替换子选择中的 4
状态,具体取决于我们当前是否要拉取 position
或 position2
作为统一的 position
。外部选择继续使用与以前相同的逻辑。
关于mysql - 使用 SUM 计算多个表中的数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/7537381/