Re: Much Ado about Nothing

David Cressey says...
>Every occurrence of an SQL NULL can be construed as a consequence of an
>outer join.

Here is a formal way to do that:

Given a table T=(c1, c2, ..., cN)

1. Add a column 'pk' to T such that pk->c1 pk->c2 .. pk->cN Let's call a resulting table as T'
2. Define tables T1-TN as: Ti := select distinct pk,ci from T' where ci is not NULL P := select distinct pk from T'
3. Now,

T' :=
select P.pk, c1, c2, ..., cN from P, T1, T2, ..., TN where T1.pk(+) = P.pk
..
TN.pk(+) = P.pk Received on Wed Mar 07 2001 - 01:01:38 CET