Re: Data Constraints AND Application Constraints

"David Cressey" <david.cressey_at_earthlink.net> wrote:

>Absolutely, yes. Let's say that a certain field in a data entry form has to
>have a number in the range 20,000 to 99,000, and may not be left blank.

> The DBMS can better use its
> resources if it doesn't get distracted by this stuff.

But surely for a rule like the one above, you would also implement a constraint in the db?

Rules that are beyond the scope of a db obviously can't be there, but if they're not beyond its scope, then they should be! I do agree that programmers should perform a check at the app level, but as the number of apps pointing at the db goes up, the probability of error increases exponentially.

>The one place where I don't think the application should perform its own
>check is referential integrity. The cost is too high for the benefits.
>Keeping the reference table synchronized across multiple applications is a
>nightmare. Letting the DBMS do the check is easy.

As is letting it check for values between x and y, not null &c.

Paul...

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