mysql - 为什么group_concat为每一行带来所有产品ID

这是我的查询，它有几个连接，除了group_concat（p.product_id）和sum（p.price）部分之外，其他部分都工作得很好。

SELECT ts.name as main_name, tp.class_id, ts.step_number, GROUP_CONCAT(p.product_id) as product_id, SUM(p.price) as price
from template as t
JOIN template_step as ts on ts.template_id=t.template_id
JOIN template_product as tp on tp.template_id=ts.template_id
JOIN product as p on p.product_id=tp.product_id
JOIN product_description as pd on pd.product_id=p.product_id
where t.template_id = '59'
group by tp.class_id, ts.step_number
ORDER by ts.step_number, tp.class_id

问题是返回产品id的元素和sum字段重复
这是我的查询数据

Networking  1   1    88,156,151,275,48,101,274,133,154,125,135,148,63,63    3070.0000
Networking  2   1    275,235,164,274,154,124,169,148,62,98,62,277,191,270   3695.0000
Networking  3   1    92,98,216,181,133,187,272,154,274,148,126,62,62,165    4970.0000
Back Office 1   2    63,88,156,151,275,48,101,274,133,154,125,135,148,63    3070.0000
Back Office 2   2    275,235,164,274,154,124,169,148,62,98,62,277,191,270   3695.0000
Back Office 3   2    62,165,92,98,216,181,133,187,272,154,274,148,126,62    4970.0000
Data Back   1   3    148,63,63,88,156,151,275,48,101,274,133,154,125,135    3070.0000
Data Back   2   3    270,275,235,164,274,154,124,169,148,62,98,62,277,191   3695.0000
Data Back   3   3    62,62,165,92,98,216,181,133,187,272,154,274,148,126    4970.0000
Kitchen     1   4    135,148,63,63,88,156,151,275,48,101,274,133,154,125    3070.0000

每个类只应返回1或2个产品ID。如果有任何其他信息我可以提供帮助别人帮助我我可以提供任何..db结构..ext..

最佳答案

GROUP_CONCAT()不会删除重复行，除非您使用DISTINCT：

GROUP_CONCAT([DISTINCT] expr [,expr ...]
             [ORDER BY {unsigned_integer | col_name | expr}
                 [ASC | DESC] [,col_name ...]]
             [SEPARATOR str_val])