Hi Josef,

> Could anybody help me with a query-statement to find out primary- and
> foreign-key fields of a Firebird database.

Look at RDB$RELATION_CONSTRAINTS and RDB$REF_CONSTRAINTS
in combination with RDB$INDICES.

With regards,

Martijn Tonies
Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL
Server.
Upscene Productions
http://www.upscene.com