关系代数和关系演算是逻辑等价的:对于任何代数表达式,都有一个等价的演算表达式,反之亦然。 Date, Christopher J. An Introduction to Database Systems 8th. Addison Wesley. 2004. ISBN 0-321-19784-4. 关系模型 关系演算
Holloway, Waymon L., Rogers, Raymond R., Rahantarisoa, Lydia J., Kemp, Addison D., Andriamialison, Haingoson. First cranial remains of a gondwanatherian
Systems, 2004, ISBN 0-321-19784-4 A Guide to the SQL standard, 4th ed., Addison Wesley, USA 1997, ISBN 978-0-201-96426-4 Databases, Types, and the Relational