SQL：如何在聚合 Select 语句中包含非聚合

Question

我在 Teradata 查询下面有这个：

create volatile table Sales_Record as (select max(a2.MDL_DESC),max(a3.DMD_DESC) FROM 
MDL_DD_DESC a2, DMD_DD_DESC a3);

当尝试使用以下内容执行查询时：

create volatile table Sales_Record as (select a1.SAL_DT SAL_DT,max(a2.MDL_DESC),max(a3.DMD_DESC) FROM SAL_DD_DT a1,
MDL_DD_DESC a2, DMD_DD_DESC a3);

出现错误：

Selected non-aggregate values must be part of the associated group.

如何在聚合函数的查询中添加a1.SAL_DT SAL_DT？

Answer 1

你需要一个GROUP BY clause:

select a1.SAL_DT SAL_DT,max(a2.MDL_DESC),max(a3.DMD_DESC) 
FROM SAL_DD_DT a1, MDL_DD_DESC a2, DMD_DD_DESC a3 
GROUP BY a1.SAL_DT

您确定这就是您想要加入这些表格的方式吗？似乎您得到了它们之间所有可能组合的产物，没有任何东西可以将表格相互关联，这很少是任何人想要的。