SQL Query with wrong result

Question

Hello.
I have a query with LEFT OUTER JOIN that I think returns invalid results. Here are the problem details:
CREATE TABLE DOGERR(
IdDog INTEGER,
SfPdg CHAR(1),
IdVpl INTEGER,
SfVpGot INTEGER,
SfZrr CHAR(1)
INSERT INTO DOGERR(IdDog, SfPdg, IdVpl, SfVpGot, SfZrr) VALUES (1, 'S', 1, 1, '7');
INSERT INTO DOGERR(IdDog, SfPdg, IdVpl, SfVpGot, SfZrr) VALUES (2, 'S', 1, 1, '7');
INSERT INTO DOGERR(IdDog, SfPdg, IdVpl, SfVpGot, SfZrr) VALUES (3, '$', 1, 2, 'C');
COMMIT;
CREATE UNIQUE INDEX DOGERR_PK ON DOGERR(IdDog);
And now the query:
SELECT D.IdDog, D.SfPdg, D.IdVpl, D.SfVpGot, D.SfZrr, T.IdVpl AS IdVplJoin, T.SfVpGot AS SfVpGotJoin, T.SfZrr AS SfZrrJoin
FROM DOGERR D
LEFT OUTER JOIN (SELECT * FROM DOGERR WHERE SfPdg = 'S' OR SfPdg = 'S') T ON
T.IdVpl = D.IdVpl AND T.SfVpGot = D.SfVpGot AND T.SfZrr = D.SfZrr
WHERE
D.IdDog = 3
AND D.SfVpGot = 2
AND D.SfZrr = 'C';
This query should (by my understanding) return only one row in wich the joined subquery columns should be NULL. And indeed query returns only one row on Oracle Database 10g Release 10.2.0.1.0 - Production and on Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production:
IDDOG = 3, SFPDG = "$", IDVPL = 1, SFVPGOT = 2, SFZRR = "C", IDVPLJOIN = NULL, SFVPGOTJOIN = NULL, SFZRRJOIN = NULL
But on Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production it returns TWO rows:
IDDOG = 3, SFPDG = "$", IDVPL = 1, SFVPGOT = 2, SFZRR = "C", IDVPLJOIN = 1, SFVPGOTJOIN = 1, SFZRRJOIN = "7"
IDDOG = 3, SFPDG = "$", IDVPL = 1, SFVPGOT = 2, SFZRR = "C", IDVPLJOIN = 1, SFVPGOTJOIN = 1, SFZRRJOIN = "7"
And now the interesting part: any of the following modified versions of query works even on Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - 64bit Production, although modifications should not modify the result set:
-- Removed unnecessary WHERE conditions
SELECT D.IdDog, D.SfPdg, D.IdVpl, D.SfVpGot, D.SfZrr, T.IdVpl AS IdVplJoin, T.SfVpGot AS SfVpGotJoin, T.SfZrr AS SfZrrJoin
FROM DOGERR D
LEFT OUTER JOIN (SELECT * FROM DOGERR WHERE SfPdg = 'S' OR SfPdg = 'S') T ON
T.IdVpl = D.IdVpl AND T.SfVpGot = D.SfVpGot AND T.SfZrr = D.SfZrr
WHERE
D.IdDog = 3;
-- Removed unnecessary OR condition in subquery
SELECT D.IdDog, D.SfPdg, D.IdVpl, D.SfVpGot, D.SfZrr, T.IdVpl AS IdVplJoin, T.SfVpGot AS SfVpGotJoin, T.SfZrr AS SfZrrJoin
FROM DOGERR D
LEFT OUTER JOIN (SELECT * FROM DOGERR WHERE SfPdg = 'S') T ON
T.IdVpl = D.IdVpl AND T.SfVpGot = D.SfVpGot AND T.SfZrr = D.SfZrr
WHERE
D.IdDog = 3
AND D.SfVpGot = 2
AND D.SfZrr = 'C';
-- Removed columns from joined subquery from SELECT part
SELECT D.IdDog, D.SfPdg, D.IdVpl, D.SfVpGot, D.SfZrr, T.IdVpl AS IdVplJoin, T.SfVpGot AS SfVpGotJoin
FROM DOGERR D
LEFT OUTER JOIN (SELECT * FROM DOGERR WHERE SfPdg = 'S' OR SfPdg = 'S') T ON
T.IdVpl = D.IdVpl AND T.SfVpGot = D.SfVpGot AND T.SfZrr = D.SfZrr
WHERE
D.IdDog = 3
AND D.SfVpGot = 2
AND D.SfZrr = 'C';
NOTE: the query itself is a little stupid but this is just to demonstrate the problem. We have faced this problem at a customer with our real-world query.
So, my question is: why different results ?
Thanks.
David

Answer 1

hi,
welcome to the forum,
don't have a solution, but I thought I'd let you know that the first SQL statement only returns 1 row on 10gR2
SQL> SELECT D.IdDog, D.SfPdg, D.IdVpl, D.SfVpGot, D.SfZrr, T.IdVpl AS IdVplJoin, T.SfVpGot AS SfVpGo
tJoin, T.SfZrr AS SfZrrJoin
  2  FROM DOGERR D
  3  LEFT OUTER JOIN (SELECT * FROM DOGERR WHERE SfPdg = 'S' OR SfPdg = 'S') T ON
  4  T.IdVpl = D.IdVpl AND T.SfVpGot = D.SfVpGot AND T.SfZrr = D.SfZrr
  5  WHERE
  6  D.IdDog = 3
  7  AND D.SfVpGot = 2
  8  AND D.SfZrr = 'C';
     IDDOG S      IDVPL    SFVPGOT S  IDVPLJOIN SFVPGOTJOIN S
         3 $          1          2 C
SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for Solaris: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production