RE: SQL to retrieve all distinct records

From: Jacques Kilchoer <Jacques.Kilchoer_at_quest.com>
Date: Thu, 15 Apr 2004 14:09:59 -0700
Message-ID: <B5C5F99D765BB744B54FFDF35F60262109F877AF@irvmbxw02>

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_at_hotmail.com>
> >
> >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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Received on Thu Apr 15 2004 - 17:43:58 CDT