Mở rộng các phép toán quan hệ cho null phụ thuộc ngữ cảnh

Bùi Thị Thúy Hiền

Abstract


In this paper, we apply the concept of model introduced in [2] to define extended relational algebra operators. It is proved that these extensions have properties which are formally stated as being adequate and precise.



Journal of Computer Science and Cybernetics ISSN: 1813-9663

Published by Vietnam Academy of Science and Technology