Re: using multiple subtables efficiently

From: liz lawson <news_at_charitycards.co.uk>
Date: Thu, 27 Sep 2001 11:56:32 +0100
Message-Id: <1001587958.23752.1@hebe.uk.clara.net>

>not post any DDL, so people trying to help you have to make stupid
>wild ass guesses about what you are doing.
>

Sorry - I'm learning using mySQL so the DDL wouldn't be appropriate (table definitions do not include relationships, foreign keys etc). ). I can see the concepts but I wouldn't be able to write the sort of DDL you are looking for - I'd get it too wrong to be any use!

I guess this group isn't appropriate to my level but I'd appreciate being pointed towards a resource that might help answer my question?

Thanks

Liz

######## clarified summary of original question############

Given a table A in which each row can have a 1 to 1 relationship to one or no other tables a,b,c,d,e,..n, should the existence of a related row in tables a,b,c,d,e...n be determined using a multiple outer join, eg

SELECT...
FROM TABLE A

OUTER JOIN a ON a.id=A.id,
OUTER JOIN b ON b.id=A.id,
OUTER JOIN a ON c.id=A.id,
OUTER JOIN a ON d.id=A.id,
OUTER JOIN a ON e.id=A.id,

...
OUTER JOIN a ON n.id=A.id

Or by including a field in table A that specifies which if any of tables a,b,c,d,e...n contains a related row?

##############################################

Received on Thu Sep 27 2001 - 05:56:32 CDT