Ken,

See inline

>Yeah - that would work, just seems kludgey (sp?) to me. I was hoping for something more like:
>
>CONSTRAINT alphanum_only check (ISALPHANUM(vcolumn)) with the "ISALPHANUM" being a built in funtion. Surely lots of people/cases would need this wouldn't you think?

It would be nice. I don't think I've ever seen a native function like that in any language.

>On another note - what kind of performance hit can I expect with lots of these type checks in the database?

Constraints are very fast. They are checked before any data modifications are actually made. I wouldn't suspect that you would see anything noticable.

>As for 3-T issue, seems to me that if you don't protect in the database, someone could get in and screw things up woith Excel or similar huh?

That's always been the argument used by DBA types (including myself) for implementing most of the rules in the data store. You can prevent someone from bypassing the middle tier through the use of Application Roles.

-Mike