Citat:
Originalno napisao ivanhoe
evo ovako:
|
Nisam siguran da razumem ideju:
Kôd:
test=# create table dpt (id1 integer, id2 integer, broj integer);
CREATE TABLE
test=# insert into dpt values (1, 2, 10);
INSERT 0 1
test=# insert into dpt values (1, 2, 10);
INSERT 0 1
test=# insert into dpt values (2, 1, 10);
INSERT 0 1
test=# insert into dpt values (2, 1, 10);
INSERT 0 1
test=# insert into dpt values (1, 3, 10);
INSERT 0 1
test=# SELECT t1.id1, t1.id2, t1.broj + coalesce(t2.broj, 0) AS broj
FROM dpt t1
LEFT JOIN dpt t2 ON (t1.id1 = t2.id2 AND t1.id2 = t2.id1);
id1 | id2 | broj
-----+-----+------
1 | 2 | 20
1 | 2 | 20
1 | 2 | 20
1 | 2 | 20
1 | 3 | 10
2 | 1 | 20
2 | 1 | 20
2 | 1 | 20
2 | 1 | 20
(9 rows)