Relation-type database expansion method and relation-type database expansion system

The invention provides a relation-type database expansion method and a relation-type database expansion system. A database table comprises expansion fields, wherein default format texts serialized by class files are saved in the expansion fields; content of the default format texts is read from the expansion fields, and the content of the default format texts is de-serialized into matched class files; the operation on the class files are responded and the operated class files are serialized into the default format texts and then saved in the expansion fields. By means of the method and system, the design development work and change work of database table for every update can be reduced.