Current database reverse engineering researches presume that the information regarding semantics of attributes, primary keys, and foreign keys in database tables is complete. However, this may not be the case. In this paper, we present a process that extracts an extended entity relationship diagram from a table-based database with little descriptions for the fields in its tables and no description for keys. The primary inputs of our approach are system display forms and table schema. An extended ER diagram is successfully extracted in a case study.