Re: How to join when NULL is the common value ?

From: Niall Litchfield <n-litchfield_at_audit-commission.gov.uk>
Date: Sat, 21 Oct 2000 12:37:45 +0100
Message-ID: <8srv69$l6c$1@soap.pipex.net>

Why would you wish to do this? It is utterly , utterly meaningless.

Consider a self joined address table with the following rows

empname add1

Niall         NULL
dili666      NULL

If you join on add1 as you suggest then you'd join my address record (where my address is unknown data) to (amongst other rows) your address which is also unknown. As a Null column value means you can say Nothing at all about that data how on earth can you possibly join on it?

--
Niall Litchfield
Oracle DBA
Audit Commission UK
<dili66_at_my-deja.com> wrote in message news:8sqcns$rjt$1_at_nnrp1.deja.com...


> Hi, At a first glance it appears that when someone

> would like to join two tables over some column then

> a row with a NULL value in one of the columns will

> not be joined with a row with a NULL value in

> the other table.  Do you know if there is a switch

> to allow this type of join ?

>

> Thank you.

>

> D

>

>

> Sent via Deja.com http://www.deja.com/

> Before you buy.

Received on Sat Oct 21 2000 - 06:37:45 CDT