Re: help on a query

A query that should get the job done is:

SELECT registration_id
FROM registrations r
WHERE NOT EXISTS (
SELECT 1
FROM receipts
WHERE registration_id = r.registration_id
);

There might be a more efficient version with JOINs that don't require a
subquery, but this should get you started.

-tfo

On Oct 7, 2004, at 10:03 PM, Michelle Murrain wrote:

> Hi all,
>
> This is one of those things I know I should know, but it's not coming
> to me. It's probably really simple.
>
> I have two related tables, registrations and receipts, related by the
> field registration_id.
>
> So registrations looks kinda like:
>
> registration_id bigint (primary key)
> foo varchar(10)
> bar varchar(20)
>
> and receipts looks like:
>
> receipt_id bigint (primary key)
> registration_id bigint (foreign key)
> amount float
> baz varchar(10)
>
> If someone has paid, there is a row in the receipts table for that
> registration ID#.
>
> I need to find a list of the registration IDs that *don't* have an
> entry in the receipts table.
>
> Thanks in advance!!!
> --
> .Michelle
>
> --------------------------
> Michelle Murrain
> mmurrain at dbdes dot com
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> Holiness the Dalai Lama
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