Comments on: Why use Constraints in SQL ?

By: Heartburn Home Remedy

Heartburn Home Remedy — Wed, 15 Apr 2009 11:59:41 +0000

Hey, nice tips. I’ll buy a bottle of beer to that person from that forum who told me to go to your blog

By: water softening systems

water softening systems — Thu, 29 Jan 2009 13:50:43 +0000

Does anyone use database constraints *instead* of app logic to enforce business rules?

By: Loïc Hoguin

Loïc Hoguin — Tue, 27 Jan 2009 11:03:44 +0000

I agree, great post. I would be glad if more people used constraints in their projects, they’re really useful in all parts of your project, including development, and prevent problems. Most people don’t know about them unfortunately. Ed: great idea, it would prove quite powerful. It would require caching to be efficient but that should not be a problem since the schema usually don’t change often.

By: Ed Lecky-Thompson

Ed Lecky-Thompson — Tue, 27 Jan 2009 11:02:54 +0000

Great article, Gaurav. One thing I do like about constraints and triggers is that by keeping an additional layer of responsibility for referential integrity within the RDBMS (as opposed to the application) it means that any third party scripts or applications which access the database automatically enjoy the same level of protection as the web application. RI can be destroyed in a second by an errant PERL script that somebody quickly knocked up to solve a problem late on a Friday afternoon; using constraints and triggers gets around this. One thing you might be interested in looking at is writing some PHP classes which can read the database constraints and trigger schema and use it to automatically build validation logic in your application; that way you don’t have to constantly ‘match’ your application validation to the database schema, because it’s pulled out automatically on the fly.