| 释义 |
DictionarySeerelationalrelational calculus
relational calculus (database)An operational methodolgy, founded on predicate calculus, dealing with descripitive expressions that areequivalent to the operations of relational algebra. Codd's reduction algorithm can convert from relational calculus torelational algebra.
Two forms of the relational calculus exist: the tuple calculus and the domain calculus.
["An Introduction To Database Systems" (6th ed), C. J. Date,Addison Wesley].relational calculusThe rules for combining and manipulating relations; for example De Morgan's law, "the complement of a union is equal to the union of the complements." |