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finding common records from two tables

Posted on 2013-01-07
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Last Modified: 2013-02-05
I have two tables with same columns  i have key based upon that key i want to see  if i have any dups or common records for that two tables

how can i do that.

Thanks
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Question by:sam2929
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Expert Comment

by:slightwv (䄆 Netminder)
ID: 38752661
Use intersect?

select key_col1, key_col2 from table1
intersect
select key_col1, key_col2 from table2
/

You could join them as well but I figure intersect will be faster.
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Expert Comment

by:slightwv (䄆 Netminder)
ID: 38752663
forgot the join:

select t1.keycol1, t1.keycol2 from tab1 t1, tab2 t2
where t1.keycol1=t2.keycol1 and t1.keycol2=t2.keycol2;
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Expert Comment

by:ajexpert
ID: 38753060
You can also try out EXISTS clause.

assuming you want data only from table1 that EXISTS in table2

select t1.* from tab1 t1
WHERE EXISTS
(select 1 from tab2 t2
where t1.col1=t2.col1
and t1.col2=t2.col2)
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Author Comment

by:sam2929
ID: 38753126
Now i want to delete the dups how can i do that
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Expert Comment

by:slightwv (䄆 Netminder)
ID: 38753138
Something like:
Delete from table1 where rowid in
(
Select t1.rowid
From ...whatever select you wanted to use
)

If you want to delete from table2, just switch the names.
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LVL 76

Expert Comment

by:slightwv (䄆 Netminder)
ID: 38753141
Oops.

That deletes all rows.  If that isn't what you want, just let us know.
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Author Comment

by:sam2929
ID: 38753305
No i don't want to delete all rows

table a looks like

doc_num    yr           line
123            2010         1
234            2010         1

table b looks like
doc_num    yr           line
123            2010         1
345           2010         1

i want final result as
doc_num    yr           line
234            2010         1

table b looks like
doc_num    yr           line
123            2010         1
345           2010         1
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Accepted Solution

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slightwv (䄆 Netminder) earned 500 total points
ID: 38753339
I didn't mean ALL rows.  I just meant all 'matching' rows. That is what you showed in the results.

When trying things like this, set up a simple test case to see what happens.

Here is a complete test using your sample data.  If you do not get the expected results, please add to it and show where it fails.

drop table taba purge;
create table taba(doc_num number, yr number, line number);

drop table tabb purge;
create table tabb(doc_num number, yr number, line number);

insert into taba values(123,2010,1);
insert into taba values(234,2010,1);

insert into tabb values(123,2010,1);
insert into tabb values(345,2010,1);
commit;

delete from taba
where (doc_num,yr,line) in (select doc_num,yr,line from tabb);
commit;

select * from taba;
select * from tabb;

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