Most of the system development are revamp of the existing computer system. Many existing data need to be migrated to the new system and it must involve some kinds of data conversion. Data conversion need to be done since the data structure of the existing and the new system is different.

The purpose of this book is to list out the essential task, from identifying what data to migrate, how they are stored in the old system, how to map and recreate them in the new system, how to check if the data is properly migrated and converted. It covers procedures of what to do, how to do and how to verify.