Oracle vs PostgreSQL Develop（24） - subquery with agg function

来源：这里教程网时间：2026-03-14 19:44:19 作者：

准确的表达应该是在子查询的having条件中出现agg函数且依赖父查询的相关字段时，Oracle支持而PG不支持。
**Oracle**
创建表，插入数据，执行查询，OK！
```
TEST-orcl@DESKTOP-V430TU3>drop table tbl1;
Table dropped.
TEST-orcl@DESKTOP-V430TU3>drop table tbl2;
Table dropped.
TEST-orcl@DESKTOP-V430TU3>drop table tbl3;
Table dropped.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>create table tbl1 (id int,c1 int,c2 int,c3 int);
Table created.
TEST-orcl@DESKTOP-V430TU3>create table tbl2 (id int,c1 int,c2 int,c3 int);
Table created.
TEST-orcl@DESKTOP-V430TU3>create table tbl3 (id int,c1 int,c2 int,c3 int);
Table created.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(2,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(2,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl1 values(3,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(2,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(2,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl2 values(3,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>truncate table tbl3;
Table truncated.
TEST-orcl@DESKTOP-V430TU3>insert into tbl3 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>insert into tbl3 values(1,1,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>commit;
Commit complete.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>truncate table tbl3;
Table truncated.
TEST-orcl@DESKTOP-V430TU3>insert into tbl3 values(1,2,1,1);
1 row created.
TEST-orcl@DESKTOP-V430TU3>
TEST-orcl@DESKTOP-V430TU3>select a.id,sum(a.c1) as sum_c1,sum(a.c2) as sum_c2
  2  from tbl1 a,tbl2 b
  3  where a.id = b.id
  4    and exists (select 1 from tbl3 c where c.id = a.id group by c.id having sum(c.c1) > sum(a.c1))
  5  group by a.id;
        ID     SUM_C1     SUM_C2
---------- ---------- ----------
         1          9          9
TEST-orcl@DESKTOP-V430TU3
```
不过，就算Oracle支持这样的写法，也不建议这样来写，原因是SQL语义理解起来并不友好，难以理解。
**PG**
创建表，插入数据，执行查询，出错。
```
[pg12@localhost ~]$ psql
Expanded display is used automatically.
psql (12.1)
Type "help" for help.
[local:/data/run/pg12]:5120 pg12@testdb=# drop table tbl1;
s(1,1,1,1);
insert into tbl1 values(1,1,1,1);
insert into tbl2 select * from tbl1;
insert into tbl2 select * from tbl1;
insert into tbl3 select * from tbl1;
commit;
ERROR:  table "tbl1" does not exist
[local:/data/run/pg12]:5120 pg12@testdb=# drop table tbl2;
ERROR:  table "tbl2" does not exist
[local:/data/run/pg12]:5120 pg12@testdb=# drop table tbl3;
ERROR:  table "tbl3" does not exist
[local:/data/run/pg12]:5120 pg12@testdb=# 
[local:/data/run/pg12]:5120 pg12@testdb=# create table tbl1 (id int,c1 int,c2 int,c3 int);
CREATE TABLE
[local:/data/run/pg12]:5120 pg12@testdb=# create table tbl2 (id int,c1 int,c2 int,c3 int);
CREATE TABLE
[local:/data/run/pg12]:5120 pg12@testdb=# create table tbl3 (id int,c1 int,c2 int,c3 int);
CREATE TABLE
[local:/data/run/pg12]:5120 pg12@testdb=# 
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl1 values(1,1,1,1);
INSERT 0 1
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl1 values(1,1,1,1);
INSERT 0 1
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl1 values(1,1,1,1);
INSERT 0 1
[local:/data/run/pg12]:5120 pg12@testdb=# 
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl2 select * from tbl1;
INSERT 0 3
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl2 select * from tbl1;
INSERT 0 3
[local:/data/run/pg12]:5120 pg12@testdb=# 
[local:/data/run/pg12]:5120 pg12@testdb=# insert into tbl3 select * from tbl1;
INSERT 0 3
[local:/data/run/pg12]:5120 pg12@testdb=# 
[local:/data/run/pg12]:5120 pg12@testdb=# commit;
WARNING:  there is no transaction in progress
COMMIT
[local:/data/run/pg12]:5120 pg12@testdb=# select a.id,sum(a.c1) as sum_c1,sum(a.c2) as sum_c2
pg12@testdb-# from tbl1 a,tbl2 b
pg12@testdb-# where a.id = b.id
pg12@testdb-#   and exists (select 1 from tbl3 c where c.id = a.id group by c.id having sum(c.c1)  = sum(a.c1))
pg12@testdb-# group by a.id;
ERROR:  aggregate functions are not allowed in WHERE
LINE 4: ...ere c.id = a.id group by c.id having sum(c.c1)  = sum(a.c1))
                                                             ^
[local:/data/run/pg12]:5120 pg12@testdb=# 
```
出现的错误是“aggregate functions are not allowed in WHERE”，但条件明明在having怎么报WHERE中出现agg函数呢？原因是PG认为条件sum(c.c1)  = sum(a.c1)中的a.c1出现在父查询中，该条件认为是WHERE中的条件。
**参考资料**
N/A