> http://www.postgresql.org/docs/8.1/interactive/functions-matching.html
>
> Any of these CHECK expressions should work:
>
> CHECK (alpha_only SIMILAR TO '[A-Za-z]+')
> CHECK (alpha_only ~ '^[A-Za-z]+$')
> CHECK (alpha_only ~* '^[a-z]+$')
>
> Unfortunately, even though SIMILAR TO has been standard SQL for
> several years, not all databases implement it. Many databases
> do support regular expressions but generally via a non-standard
> syntax (as PostgreSQL does with its ~, ~*, !*, and !~* operators).
Thanks for the link!
Regards,
Richard Broersma Jr.