have two questions:
table has 2 columns and both them defined PK. Everything is ok until
table gets empty (removed all data) and insert is called - got error
saying, that PK is violated & etc info. Is this caused by the fact,
that PK consists of all (2) table columns? or it's strongly advised to
have additional ID column for the table? FB1.5.x

need to implement computations on the server side - fear, that some of
them would require complex logic and work with the selected dataset's.
How to implement them - use SQL in the SP's (when question, how to
work with the selected dataset's - create internal views for them?) or
to write UDF's? what about performance in both cases? any other
underwater rocks?