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Conjunctive query
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<p>In <a href="/facts/Database_theory/unyQa3cK">database theory</a>, a conjunctive query is a restricted form of <a href="/facts/First-order_logic/lcISqWIg">first-order</a> queries using the <a href="/facts/Logical_conjunction/62uyyn1d">logical conjunction</a> operator. Many first-order queries can be written as conjunctive queries. In particular, a large part of queries issued on <a href="/facts/Relational_database/pEKGmJLy">relational databases</a> can be expressed in this way. Conjunctive queries also have a number of desirable theoretical properties that larger classes of queries (e.g., the <a href="/facts/Relational_algebra/7tjTFXdf">relational algebra</a> queries) do not share. </p>