"Darren New" <dne### [at] sanrrcom> wrote in message 
news:48ec5d23$1@news.povray.org...
> Gail wrote:

>> Depending how many columns are only applicable to one account type, I 
>> might take a short cut and put everything in one table. It does depend 
>> though.
>
> That doesn't really solve the consistency problem, tho. You could still 
> wind up with an account where all the details are null, for example.

For that you could use check constraints.

ALTER TABLE Accounts ADD CONSTRAINT ck_AccountType CHECK (AccountType = 
'CreditCard' AND exxpirationdate IS NOT NULL)
etc

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