On Mon, May 25, 2009 at 11:03 AM, Olaf Kluge <olaf.kluge@...> wrote:

> Examples:
> LF200 is right
> LF 9999 is right
> 87987 is right
> XY888 is not valid

With Firebird 2.5 you can use a regular expression:
(?:LF)?\s*?\d+

Here's the syntax details:
http://www.firebirdsql.org/rlsnotesh/rlsnotes25.html#rnfb25-dml-regex

hth,
--
Douglas Tosi
www.sinatica.com