As in most things in software engineering, it's a matter of tradeoff. Consider for instance the case where multiple applications access the database. You could

As in most things in software engineering, it's a matter of tradeoff. Consider for instance the case where multiple applications access the database. You could either build a service abstracting, or you could build your validation layer in the database via stored procedures (maybe you can't afford the latency of the service), in which case you'll appreciate the additional safety.