Question

是否可以通过聚合函数进行联接？

假设我们在主查询中有

Select MIN(id) as MINID, product AS PRODUCT, SUB.produkt_name, SUB.product_type
FROM log_table
GROUP BY PRODUCT, SUB.produkt_name, SUB.product_type

我要加入一个有关产品的所有信息的子查询：

JOIN（某些子查询）SUB ON LOG_TABLE.MINID = SUB.ID

Answer 1

您可以在JOIN之前进行汇总。

这是您想要的吗？

SELECT l.MINID, l.product AS PRODUCT, SUB.produkt_name, SUB.product_type
FROM (some subquery
     ) SUB JOIN
     (SELECT l.PRODUCT, MIN(l.id) as MINID
      FROM log_table l
      GROUP BY l.PRODUCT
     ) l
     ON l.MINID = SUB.ID
GROUP BY l.PRODUCT, SUB.produkt_name, SUB.product_type

Answer 2

您可以执行以下操作

select * from
(
Select MIN(id) as MINID, product AS PRODUCT, SUB.produkt_name, SUB.product_type
FROM log_table
GROUP BY PRODUCT, SUB.produkt_name, SUB.product_type
)A JOIN (some subquery) SUB ON A.MINID=SUB.ID

您可以按具有聚合功能的列联接吗？

2 个答案: