Information systems have evolved from simple file processing systems to powerful database systems. Relational Databases put the layout and form into the unchanging metadata and gave us "record once" systems. Unfortunately, the "real world" upon which databases are modelled constantly changes. These changes may affect the schema for a variety of reasons. Different formalisms have been developed to deal with schema changes aiming to preserve information capacity and semantic correctness. ...
Information systems have evolved from simple file processing systems to powerful database systems. Relational Database...