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Thread: How to join to delete

How to join to delete

From
"Chris Velevitch"
Date:
I'm using pg 7.4.5 on Win XP SP1.

I want to delete rows from a table B, but need to join it to another
table A in order to select the rows in B to be deleted.

Eg. Delete from A join B on (A.bk = B.bk) where A.ak = x;

but only delete rows from B.

How do I acheive this?


Chris
--
Chris Velevitch
Manager - Sydney Flash Platform Developers Group
www.flashdev.org.au

Re: How to join to delete

From
Noel Faux
Date:
Hi Chris,

I think the best bet would be to use a nested select:

Delete from A WHERE A.bk = (SELECT bk FROM B) where A.ak = x;

Cheers
Noel

Chris Velevitch wrote:
> I'm using pg 7.4.5 on Win XP SP1.
>
> I want to delete rows from a table B, but need to join it to another
> table A in order to select the rows in B to be deleted.
>
> Eg. Delete from A join B on (A.bk = B.bk) where A.ak = x;
>
> but only delete rows from B.
>
> How do I acheive this?
>
>
> Chris
> --
> Chris Velevitch
> Manager - Sydney Flash Platform Developers Group
> www.flashdev.org.au
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings
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Re: How to join to delete

From
Richard Huxton
Date:
Chris Velevitch wrote:
> I'm using pg 7.4.5 on Win XP SP1.

The first official release for Windows was 8.0, and there have been
several bugfixes to 7.4.x since then. Upgrade as soon as is practical.

> I want to delete rows from a table B, but need to join it to another
> table A in order to select the rows in B to be deleted.
>
> Eg. Delete from A join B on (A.bk = B.bk) where A.ak = x;
>
> but only delete rows from B.

Perhaps something like:
  DELETE FROM B WHERE bk IN (SELECT ak FROM A WHERE ak2 = x)

Or maybe rephrase it as EXISTS for 7.4

--
   Richard Huxton
   Archonet Ltd

Re: How to join to delete

From
"Chris Velevitch"
Date:
On 5/2/06, Richard Huxton <dev@archonet.com> wrote:
> Chris Velevitch wrote:
> > I'm using pg 7.4.5 on Win XP SP1.
>
> The first official release for Windows was 8.0, and there have been

I'm the cygwin version of pg for testing.

> several bugfixes to 7.4.x since then. Upgrade as soon as is practical.

I'm deploying to a shared hosted database and they are currently
supporting 7.4.x.


Chris
--
Chris Velevitch
Manager - Sydney Flash Platform Developers Group
www.flashdev.org.au