finding common records from two tables

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.

forgot the join:

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

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)

Now i want to delete the dups how can i do that

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.

Oops.

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

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