Business rules are often specified only implicitly by applications to express user-defined constraints. OCL provides the chance to explicitly and automatically deal with business rules when building object-oriented applications. We investigate how OCL constraints can be handled in database applications as one of the most important kind of business applications. Based on our OCL toolset prototype and earlier research work we particularly experiment with various strategies for the evaluation of OCL constraints in object-oriented applications which use relational databases. For this work, a flexible SQL code generator is needed which can be used and adapted for different relational database systems and different object-to-table mappings. We implement such a database tool as an additional module for our OCL toolset using XML techniques.