Normal select statement error!??

Question

Hello All,
I have a table with primary key (antrag_nr, beladeflag, stempel)
Desc test88
Name Null? Type
ANTRAG_NR NOT NULL NUMBER
A_PROZESS NUMBER
STEMPEL NOT NULL DATE
BELADEFLAG NOT NULL VARCHAR2(1)
desc test99
Name Null? Type
ANTRAG_NR NOT NULL NUMBER
A_PROZESS NUMBER
STEMPEL NOT NULL DATE
BELADEFLAG NOT NULL VARCHAR2(1)
select * from test99;
ANTRAG_NR A_PROZESS STEMPEL B
1 3 04-JAN-05 m
2 4 04-JAN-05 m
1     4 05-JAN-05 m
select * from test88;
ANTRAG_NR A_PROZESS STEMPEL B
1 1 01-JAN-05 m
1 2 02-JAN-05 m
1 2 03-JAN-05 m
1 3 04-JAN-05 m
2 1 01-JAN-05 m
2 2 02-JAN-05 m
2     3 04-JAN-05 m
I am writing this query now and getting the below answer.
select a.antrag_nr, a.a_prozess, a.stempel, a.beladeflag from test88 a, test99 b where a.antrag_nr = b.antrag_nr and a.a_prozess <> b.a_prozess and a.stempel = (select max(stempel) from test88);
ANTRAG_NR A_PROZESS STEMPEL B
2 3 04-JAN-05 m
1     3 04-JAN-05 m
according to my query I have ’a a.a_prozess <> b.a_prozess’ but why do I get 1 3 04-jan-05 m
Please let me know where have I gone wrong!!
RGds
Karhtik krishna

Answer 1

The way your initial query was designed, checks all a_prozess available for each antrag_nr. If I change your query around I can demonstrate.
select  a.antrag_nr
,       b.a_prozess
,       a.stempel
,       a.beladeflag
from    test88 a
,       test99 b
where   a.antrag_nr = b.antrag_nr
and     a.a_prozess <> b.a_prozess
and     a.stempel = (   select max(stempel)
                        from test88
ANTRAG_NR     A_PROZESS     STEMPEL          BELADEFLAG
1          4          4-JAN-2005     m
2          4          4-JAN-2005     m