Godel's main contribution to set theory is his proof that GCH is consistent
with ZFC (assuming that ZF is consistent). For this proof he has introduced
the important ideas of constructibility of sets, and of absoluteness of
formulas. In this paper we show how these two ideas of Godel naturally
lead to a simple unified framework for dealing with computability of
functions and relations, domain independence of queries in relational
databases, and predicative set theory.