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RE: [OT] SQL question
- To: <ukha_d@xxxxxxx>
- Subject: RE: [OT] SQL question
- From: "Mark Hetherington" <mark.egroups@xxxxxxx>
- Date: Fri, 22 Mar 2002 19:10:17 -0000
- Delivered-to: mailing list ukha_d@xxxxxxx
- Mailing-list: list ukha_d@xxxxxxx; contact
ukha_d-owner@xxxxxxx
- Reply-to: ukha_d@xxxxxxx
> Say this is the child data
>
> Parent Date Comment
> 1 22/02/02 Some data
> 1 20/02/02 Some more data with the same parent
> 2 05/02/02 More data but for a different parent
> 2 01/02/02 More data for the second parent
> 3 20/02/02 Data for a third parent
>
> The result set I am after is this
> 1 22/02/02 Some data
> 2 05/02/02 More data but for a different parent
> 3 20/02/02 Data for a third parent
>
> IE the most receint comment only ?
This should do it:
SELECT DISTINCT ON (Parent) Parent,Date,Comment FROM child ORDER BY Date
DESC
It will basically sort all rows by date then select only the first row
(i.e.
the most recent entry). DESC is to ensure that we get the latest date at
the
top of the resulting table since SQL defaults to ASC.
HTH.
Mark.
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