Consistency Requirements for Subtables Consistency requirements on subtables and supertables. Each tuple of the supertable(e.g.people)can correspond to at most one tuple in each of the subtables(e.g.students and teachers) Additional constraint in SQL:1999: All tuples corresponding to each other(that is,with the same values for inherited attributes)must be derived from one tuple(inserted into one table). That is,each entity must have a most specific type We cannot have a tuple in people corresponding to a tuple each in students and teachers Database System Concepts-5th Edition,Aug 9,2005. 9.15 ©Silberschat乜，Korth and SudarshanDatabase System Concepts - 5 9.15 ©Silberschatz, Korth and Sudarshan th Edition, Aug 9, 2005. Consistency Requirements for Subtables Consistency requirements on subtables and supertables. Each tuple of the supertable (e.g. people) can correspond to at most one tuple in each of the subtables (e.g. students and teachers) Additional constraint in SQL:1999: All tuples corresponding to each other (that is, with the same values for inherited attributes) must be derived from one tuple (inserted into one table).  That is, each entity must have a most specific type  We cannot have a tuple in people corresponding to a tuple each in students and teachers