Question

我有如下查询，

select a,b,c, (select h from table 1 where field = a and field2 = b) as alias_column, d
from table 
group by a,b,c, (select h from table 1 where field = a and field2 = b) , d

我收到错误，

ORA-22818: subquery expressions not allowed here
22818. 00000 -  "subquery expressions not allowed here"
*Cause:    An attempt was made to use a subquery expression where these
           are not supported.
*Action:   Rewrite the statement without the subquery expression.
Error at Line: 84 Column: 2

我认为这是因为where clause中添加了子查询中的group by

请参阅子查询，(select * from table 1 where field = a and field2 = b)包含父表中的a和b字段。

请帮忙。

Answer 1

如果子查询（select * from table 1 where field = a and field2 = b）只返回一个值然后这应该工作：

select * from
(select a,b,c, (select * from table 1 where field = a and field2 = b) as alias_column, d
from table) 
group by a,b,c, alias_column , d

但是如果子查询（select * from table 1 where field = a and field2 = b）如果没有返回一个值，那么您将得到以下错误：

ORA-01427: single-row subquery returns more than one row
01427. 00000 -  "single-row subquery returns more than one row"

Answer 2

为什么在没有涉及聚合函数的情况下进行分组？

使用DISTINCT代替，即

SELECT DISTINCT a,b,c,
       (select * from table 1
        where field = a and field2 = b) as alias_column, d
from table

无法在Group By - Oracle中添加子查询表达式

2 个答案: