Problem with merge

Question

Hi,
I have 2 tables and I would like to insert or update everything from table2 into table1.
That I know how to do, so now the tricky part.
I would like to update a row in table1 if the data is NOT in table2.
f.x.
table1 has the following data:
1, 'test1', '2009-09-04'
2, 'test2', '2009-08-15'
3, 'test3', '2009-08-15'
table2:
2, 'test3', '2009-08-15',
3, 'test2', '2009-08-15'
This should result in table1 looking like this:
1, 'test1', NULL
2, 'test3', '2009-08-15'
3, 'test2', '2009-08-15'
- date on row 1 has been set to null since there is no data with ID 1 in table2
- second field on row2 and row3 has been changed to match that of table2
Thanks
Bjarke

Answer 1

SQL> select * from testing;
COL1                 COL2
test3                3
test2                2
test1                1
SQL> select * from testing1;
COL1       COL2
test3      new3
test2      new2
SQL> update testing set col2 = (select col2 from testing1 where testing1.col1= testing.col1)
  2  ;
3 rows updated.
SQL> select * from testing;
COL1                 COL2
test3                new3
test2                new2
test1check this.
Ravi Kumar