Abstract: A method for validating data changes made to a database is disclosed. The changes are made in the context of a transaction, and validation is performed using a rules database storing a plurality of rules. The method includes identifying a set of data entities affected by one or more data changes made in the context of the transaction. In response to an instruction to commit the transaction, data entities in the set of affected data entities are validated using rules from the rules database. The transaction is committed in dependence on the outcome of the validation.