RE: SQL to retrieve all distinct records
- From: "Jacques Kilchoer" <Jacques.Kilchoer@xxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 15 Apr 2004 14:09:59 -0700
The question you have to answer first is:
suppose I have several values of C for the A and B combination
Which value of C do I want to return?
The one with the lowest value?
The one with the highest value?
Any one (it doesn't matter which?)
e.g. in your example below:
A B C
---------- ---------- ----------
APPS APPS R1
SYS SYS2 R2
SYS SYS2 R3
...
Why do you want to return SYS - SYS2 - R2 and not SYS - SYS2 - R3? Does it have
to be SYS - SYS2 - R2 or does it matter if the query returns only one row with
SYS - SYS2 - R2?
Once you answer that question, then the expert minds on this list will help you
devise a better query.
Without knowing the answer to that question, I could suggest
select a, b, min (c) group by a, b ;
or
select a, b, max (c) group by a, b ;
> -----Original Message-----
> Alison Barak
>
> I believe I have found a solution. Just wonder if anyone else has an
> alternative or better approach?
>
> select * from testing where rowid in (select min(rowid) from
> testing group
> by a,b);
>
>
> >From: "Alison Barak" <ambarak@xxxxxxxxxxx>
> >
> >can someone assist me with formulating a query to retrieve
> all distinct
> >records. I need to retrieve all three columns a,b &c based
> on the distinct
> >of the two columns a & b.
> >
> >SQL> select * from testing;
> >A B C
> >---------- ---------- ----------
> >APPS APPS R1
> >SYS SYS2 R2
> >SYS SYS2 R3
> >DOC DOC2 R4
> >DC DC2 R5
> >DOC DOC R6
> >
> >The result should be
> >A B C
> >---------- ---------- ----------
> >APPS APPS R1
> >SYS SYS2 R2
> >DOC DOC2 R4
> >DC DC2 R5
> >DOC DOC R6
> >
> >
> >I tried using group by/having count but was not successful. Any idea?
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