Abstract: A database structure of a sort defined by an access and query language that defines tables of variables having labels and field characteristics, such as ANSI structured query language (SQL), is modified by determining the structural differences between an existing schema and a new schema, independent of database contents. The differences are processed to generate commands that are then applied to evolve an existing database from the old schema or structure to the new one. This avoids the need to dump and restructure the contents of the old database for reload into an empty new database that has been prepared to meet the new schema.