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 ...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.展开更多
文摘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.
