Database 6 relational algebra (relational algebra) function dependencies (functional dependency) __html

Reference: Relational algebra--Division Reference: Database relational algebra expression learning Note: The number of attributes (attribute) of the collection after the join for the normal join:a join B is added to the a,b number of columns (attribute) Natural Join merges all columns with the same name {σ,π,x,∪,-}->{select, Project, Product, union,difference} are called basic operators, and other algebraic operators can have their representation for X (product), if the degree of R (degree) is n, the potential (cardinality) is M, the degree (degree) of the S is J, the potential (cardinality) is k, then the degree of R X S is (N+J), and the potential is (M*K) . DIFFERENCE:R1-R2 represents all tuples that are not in the R1 R2 Reference: Function Dependencies

The above 3.5 paradigm eliminates the process of function dependencies