準確的表達應該是在子查詢的having條件中出現agg函式且依賴父查詢的相關欄位時，Oracle支援而PG不支援。

**Oracle**
建立表，插入資料，執行查詢，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

```
不過，就算Oracle支援這樣的寫法，也不建議這樣來寫，原因是SQL語義理解起來並不友好，難以理解。

**PG**
建立表，插入資料，執行查詢，出錯。
```
[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=#

```
出現的錯誤是“aggregate functions are not allowed in WHERE”，但條件明明在having怎麼報WHERE中出現agg函式呢？原因是PG認為條件sum(c.c1)  = sum(a.c1)中的a.c1出現在父查詢中，該條件認為是WHERE中的條件。

**參考資料**
N/A

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

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