Abstract: Method and system of the invention migrate data from one or more ASCII files and/or from one or more relational databases to one or more relational database tables without the need to write code. In doing so, the invention allows the user to define mapping templates and conditionals to assist in translating and transforming data values. The invention also enforces referential integrity, data dependencies, order of operations, and uniqueness constraints using a predefined set of migration rules templates that are based on the principles of relational design. The invention uses these mapping and migration rules templates to intelligently generate instructions for updating or populating relational database destination tables. The instructions control the data transfer, data translation, data transformation, data validation, foreign key insertion, and the addition of required codes and flags in the destination tables.