A DATABASE SUBLANGUAGEFOUNDEDO N THE RELATIONAL CALCULUS by E. F. Codd IBM Research Laboratory San Jose, California ABSTRACT: Three principal types of language for data base manipulation are identified: the low-level, procedure-oriented (typified by the CODASYL-proposed DML), the intermediate level, algebraic (typified by the Project M C MacAIMS A language), and the high level, relational calculus-based data sublanguage, an example of which is described in this paper. The language description is informal and stresses concepts and principles. Following this, arguments are presented for the superiority of the calculus-based type of data base sublanguage over the algebraic, and for the algebraic over the low-level procedural. These arguments are particularly relevant to the questions of intersystem compatibility and standardization. I. Introduction The two main goals of this paper are: I. 2. To describe a data base sublanguage (ALPHA) founded on the relational model [1,2] and also on the relational calculus ; To compare this calculus-oriented sublanguage with two other types of sublanguage used or proposed for data base manipulation. Two reasons for publishing this paper at this time are: l. I t exhibits a high-level approach to data base language which is basically different from that proposed by the CODASYLData
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