这是我的查询，它有一些连接，除了 GROUP_CONCAT(p.product_id) 和 SUM(p.price) 部分外，其他都运行良好。
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
问题是返回的 product_ids 和 sum 字段的元素是重复的
这是我查询的数据
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
每个类应该只返回 1 或 2 个 product_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东西..db 结构..ext..
最佳答案
GROUP_CONCAT()除非您使用 DISTINCT，否则不会删除重复的行:
GROUP_CONCAT([DISTINCT] expr [,expr ...]
[ORDER BY {unsigned_integer | col_name | expr}
[ASC | DESC] [,col_name ...]]
[SEPARATOR str_val])
关于mysql - 为什么 group_concat 会为每一行带来所有产品 ID，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6497526/