摘要
In this paper we introduce mainly the relation between general projection and outerjoin and the relation between general projection and semijoin. We also put forward pseudodistributive law of general projection. Then we provide a more mature theory about general projection.
In this paper we introduce mainly the relation between general projection and outerjoin and the relation between general projection and semijoin. We also put forward pseudodistributive law of general projection. Then we provide a more mature theory about general projection.
出处
《计算机科学》
CSCD
北大核心
1999年第6期82-84,共3页
Computer Science
