LEADING ONE KIND OF MIXED-TYPE INCOMPLETE INFORMATION INTO RELATIONAL DATABASE

in this paper, the meaning and expression of incompleteness of information in relational database are presented, and the possibility and necessity that incompleteness in different category exists simultaneously in relational database are discussed. One kind of mixed-type incomplete information is led into relational model. In order to express and process mixed-type incomplete information in relational database, a- simplified expanded relational model is given.