Re: Help writing a piece of SQL

Thanks for that Richard, it's almost what I'm after:

So where the un and dm exist then return 1 row

Where the un doestn't exist and dm does then return all sendtos' where
the dm exists not just where the un='*'

I hope that makes sense.

Thanks for you help


Nigel Bishop
ioko
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-----Original Message-----
From: Richard Huxton [mailto:dev@archonet.com]
Sent: 03 February 2006 11:02
To: Nigel Bishop
Cc: pgsql-sql@postgresql.org
Subject: Re: [SQL] Help writing a piece of SQL

Nigel Bishop wrote:
>
>      username     |            domain         |            sendto
>
+-------------+-------------------------------+-------------------------
> -----
>
>  Postmaster       | intthit08.uk.rabbit.com   | root
>  root             | intthit08.uk.rabbit.com   | is-unix@rabbit.com
>  stoat.griffin    | trusting.co.uk            |
stoat.griffin@rabbit.com
>  stoat.griffin    | trusting.com              |
stoat.griffin@rabbit.com
>  stoat.griffin    | rusty.co.uk               |
stoat.griffin@rabbit.com
>  stoat.griffin    | rusty.com                 |
stoat.griffin@rabbit.com

>  *                | trusting.com              | rusty@rabbit.com
>  *                | trusting.co.uk            | rusty@rabbit.com
>  *                | rusty.co.uk               | rusty@rabbit.com
>  *                | rusty.com                 | rusty@rabbit.com

> The query will have the username and domain passed in as variables.
> If the username and domain exist then return the sendto
> The bit I'm struggling with is if the username doesn't exist then
return
> the sendto where the domain exists
>
> e.g.  username=fred (this doesn't exist) and domain=rusty.com then
> return rusty@rabbit.com, matilda.clematis@rabbit.com,
> stoat.griffin@rabbit.com

So: if the username doesn't exist then you return ALL rows with a
matching domain? Not just username="*"?

I'm guessing I've mis-understood and you just want username="*", which
would be something like this:

SELECT sendto, 1 AS priority FROM tbl WHERE username=$1 AND domain=$2
UNION ALL
SELECT sendto, 2 AS priority FROM tbl WHERE username='*' AND domain=$2
ORDER BY priority
LIMIT 1;

Does that help at all?
--   Richard Huxton  Archonet Ltd


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