Computing approximate joins of relations based on entity chains

Because of data inconsistencies among multiple databases, it is not always possible to get exact query answers from them. The paper proposes the method based on entity chains for approximate join queries on multiple relations, and designs extended SQL query language to implement the main procedures. An entity chain consists of the entities belonging to different relations with the same or approximate linkage attribute values, and is computed by analyzing similarity of linkage attributes in different relations. Entity chains provide facilities for approximate joins, and can be used to improve efficiency of computing approximate joins on multiple relations in information systems.