Re: postgresql vs mysql

From: Richard Broersma Jr <rabroersma(at)yahoo(dot)com>
To: Erick Papadakis <erick(dot)papa(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: postgresql vs mysql
Date: 2007-02-22 02:38:46
Message-ID: 909899.75768.qm@web31811.mail.mud.yahoo.com
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> Does PostgreSQL suffer from this oddity as well? This distinction
> between an empty string and a NULL? Could you also please give me an
> example of where this would be useful from a business logic
> standpoint? Why should a NULL be different from an empty string,
> what's the big mysterious difference?

Nulls are also useful for data that is imported where there is not always a way to determine
certain field values for a record.

Now suppose in a query you want to return all record that meet your criteria as well as any that
might meet your criteria depending if the null value was actually known.

Select * from table
Where ((field1,field2,field3) = ('farmer','baker','shoemaker')) is unknown;

Now you can get all records that may meet your criteria.

Regards,
Richard Broersma Jr.

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