Re: I need some magical advice

Andreas,
Does your table has any field that can be used as primary key? Any "ID"
field?

Best,
Oliveiros

----- Original Message -----
From: "Andreas" <maps(dot)on(at)gmx(dot)net>
To: <pgsql-sql(at)postgresql(dot)org>
Sent: Thursday, January 29, 2009 11:56 AM
Subject: [SQL] I need some magical advice

> Hi,
>
> I'd like to update some records in a table.
> Those have a status_id and among other columns a varchar with a name and a
> create_date.
> The status_id is 0 if nothing was done with this record, yet.
>
> For some reasons I've got double entries which I now want to flag to -1 so
> that they can be sorted out without actually deleting them since there are
> other tables referencing them.
>
> From every group that shares the same name all should get status_id set
> to -1 where status_id = 0.
>
> The tricky bit is:
> How could I provide, that 1 of every group survives, even then when all
> have status_id = 0?
> Sometimes 2 of a group are touched so both have to stay.
>
>
> e.g.
> c_date, status_id, name
> 2008/01/01, 0, A --> -1
> 2008/01/02, 1, A --> do nothing
> 2008/01/03, 0, A --> -1
>
> 2008/01/01, 0, B --> do nothing (single entry)
>
> 2008/01/01, 0, C --> do nothing (oldest 0 survives)
> 2008/01/02, 0, C --> -1
>
> 2008/01/01, 1, D --> do nothing
> 2008/01/02, 1, D --> do nothing
>
>
>
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