如何在不同的表上使用 group_concat 和 group by 求和

Question

我有 3 个表：用户、工具，tool_assigned:

用户：

id	name	department
1	john	a
2	peter	b
3	paul	a

工具：

id	name
1	tool1
2	tool2
3	tool3

Tool_assigned:

id	id_user	id_tool	quantity
1	1	1	1
2	1	2	3
3	1	3	1
4	2	1	2
5	2	2	3
6	2	3	1
7	3	1	2
8	3	2	1
9	3	3	1

我需要得到这个结果：

id_tool	tool_name	total_quantity	summary_department
1	tool1	5	a-1, b-2, c-2
2	tool2	7	a-3, b-3, c-1
3	tool3	3	a-1, b-1, c-1

我已经尝试执行可以获得该结果的查询，但到目前为止我得到的最好结果是：

SELECT tool.id, tool.name, sum(tool_assigned.quantity) as total_quantity, 
       group_concat(user.deparment, '-', tool_asigned.quantity) as summary_department 
FROM tool_assigned 
INNER JOIN users ON tool_assigned.id_user = user.id 
INNER JOIN tools ON tool_assigned.id_tool = tool.id 
GROUP BY tools.name, users.department

请帮帮我，我已经试过了。

Answer 1

您需要两个级别的聚合：首先按工具和部门，然后仅按工具。您可以这样表述：

select t.id, t.name as tool_name, 
    sum(x.quantity) as total_quantity,  
    group_concat(x.info order by x.department) as summary_department
from tools t
inner join (
    select ta.id_tool, u.department, concat(u.name, '-', sum(t.quantity)) as info 
    from tool_assigned ta 
    inner join users on ta.id_user = u.id 
    group by ta.id_tool, u.department
) x on x.id_tool = t.id
group by t.id

Answer 2

您还可以使用 with 语句


with tools_per_dept as (
    SELECT users.department as dept,
           tool.id as tool_id,
           tool.name as tool_name,
           sum(tool_assigned.quantity) as total_quantity
    FROM tool_assigned
             INNER JOIN users ON tool_assigned.id_user = user.id
             INNER JOIN tools ON tool_assigned.id_tool = tool.id
    GROUP BY tools.name, users.department
)
select tool_id,
       tool_name,
       sum(total_quantity) as total,
       group_concat(dept, '-', total_quantity) as summary_department 
from tools_per_dept
group by tool_id, tool_name

如何在不同的表上使用 group_concat 和 group by 求和

How to SUM using group_concat with group by on differents tables

mysql

sql

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inner-join

aggregate-functions