select min(id), 产品名，sum(销量),sum(成本) from 表名 group by 产品名

为什么不在代码里进行处理，sql处理效率低下

group by 产品名 其他的sum

https://bbs.csdn.net/topics/360129756

实用 sum函数，group by 产品名，实际SQL：Select min(ID)，产品名，sum(销量),sum(成本) from 表名 group by 产品名

select *,sum(销量)，sum(成本) from 表 group by 产品名

https://www.cnblogs.com/Snowfun/p/5895600.html 解决字符串

SELECT CityName,STUFF((SELECT ',' + UserName FROM aa subTitle WHERE CityName=A.CityName FOR XML PATH('')),1, 1, '') AS A
FROM aa A
GROUP BY CityName

INSERT INTO TableName
SELECT 产品名, (select sum(销量) from tablename where 产品名='水') AS 销量, (select sum(成本) from tablename where 产品名='水') AS 成本
FROM TableName
产品名='水'

DELETE FROM TableName WHERE 产品名 IN('水');

SELECT * FROM TableName

select 产品名，sum(销量),sum(成本) from 表名 group WHERE 产品名 IN('水');