One major approach to realise database integration is to adapt and merge the database schemas by defining views. When integrating object-oriented databases, the views need to adequately support object identity and methods. View objects need to be identified on the basis of the objects they have been derived from. Methods must be callable from the query processor without impeding query optimisation. Our view system for ODMG-93 supports both declarative and procedural integration of object-oriented databases. It provides flexible integration semantics without sacrificing the optimisation potential.