SELECT DISTINCT在多列以及其他列上 [英] SELECT DISTINCT on multiple columns along with other columns
问题描述
我要运行如下查询
select distinct (columnA, columnB, columnC), columnD from MY_TABLE where columnA IS NOT NULL AND columnB IS NOT NULL AND columnC is NOT NULL;
我只想区分columnA,columnB和columnC,而不要on columnD。
但是SQL开发人员在columnA之后指向错误,
我该如何解决?
I only want distinct of columnA, columnB and columnC and NOT ON columnD. But SQL developer is pointing an error right after columnA, How can I fix this?
我尝试使用GROUP BY
I tried to fix my query using GROUP BY
select columnA, columnB, columnC, (select count(*) from TABLE2 WHERE table2columnA = myTable.columnA) from MY_TABLE myTable where columnA IS NOT NULL AND columnB IS NOT NULL AND columnC is NOT NULL GROUP BY columnA, columnB, columnC;
注意我的columnD实际上是另一个选择语句吗?
但这给了我错误
Notice that my columnD is actually another select statement? But this is giving me error
ORA-00979: not a GROUP BY expression
00979. 00000 - "not a GROUP BY expression"
这不是另一个问题的重复
This is not a duplicate of that another question
推荐答案
SELECT DISTINCT a,b,c FROM t
大致等同于:
SELECT a,b,c FROM t GROUP BY a,b,c,t
习惯使用GROUP BY语法是一个好主意,因为它更强大。
习惯使用GROUP BY语法是一个好主意,
请参见以下帖子:
It's a good idea to get used to the GROUP BY syntax, as it's more powerful. It's a good idea to get used to the GROUP BY syntax, Please see this post:
可能重复吗?
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