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Line 217: ''Datalog'' is a database definition language, which combines a relational view of data, as in the relational model, with a logical view, as in [[logic programming]]. Whereas relational databases use a relational calculus or relational algebra, with [[Relational database#Relational operations\|relational operations]], such as ''union'', ''intersection'', ''set difference'' and ''cartesian product'' to specify queries, Datalog uses logical connectives, such as ''if'', ''or'', ''and'' and ''not'' to define relations as part of the database itself. In contrast with the relational model, which cannot ~~expressive~~express recursive queries without introducing a least-fixed-point operator,<ref>Aho, A.V. and Ullman, J.D., 1979, January. Universality of data retrieval languages. In Proceedings of the 6th ACM SIGACT-SIGPLAN symposium on Principles of programming languages (pp. 110-119).</ref> recursive relations can be defined in Datalog, without introducing any new logical connectives or operators. == See also ==

Relational model: Difference between revisions