September 24, 2003 at 12:09 pm
If you have a SELECT stmt with a DISTINCT keyword, are the combination of all columns referenced distinct?
Example,
SELECT tbl1.*, tbl2.*, tbl3.* from tbl1, tbl2, tbl3
WHERE tbl1.id=tbl2.id and tbl2.id=tbl3.id
Let's say each table has 5 columns...
So the above select stmt would return only rows where all 15 columns are distinct??
That's what I think but am not finding good documentation.
Thanks.
September 24, 2003 at 12:20 pm
Here's an example:
C1 C2 C3
1 a hello
1 b candy
2 a car
2 a car
3 c pet
SELECT DISTINCT c1, c2, c3
FROM mytable
Returns:
c1 c2 c3
1 a hello
1 b candy
2 a car
3 c pet
It's the whole 'row' that needs to be distinct. That's why both rows with c1 = 1 are returned, but only one row with c1 = 2.
-SQLBill
September 24, 2003 at 12:27 pm
That's what I thought.
Thank you.
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