The art of computer programming, volume 3: (2nd ed.) sorting and searching
The art of computer programming, volume 3: (2nd ed.) sorting and searching
A relational model of data for large shared data banks
Communications of the ACM
An information algebra: phase 1 report—language structure group of the CODASYL development committee
Communications of the ACM
SEQUEL: A structured English query language
SIGFIDET '74 Proceedings of the 1974 ACM SIGFIDET (now SIGMOD) workshop on Data description, access and control
The relational data management system: A perspective
SIGFIDET '74 Proceedings of the 1974 ACM SIGFIDET (now SIGMOD) workshop on Data description, access and control
Two semantic worlds: a data base system with provision for natural language input
IJCAI'77 Proceedings of the 5th international joint conference on Artificial intelligence - Volume 1
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An increasing friendliness towards the “casual” user is one of the main characteristics of the evolution of man-machine communication systems. In the Database area, it is common opinion that this may be achieved by providing an “easy” means of communication between the user and the system and a conceptually simple data model (i.e. usable by a user who is not DP professional, but accepts a slight degree of formalization). The aim of this paper is to describe a formal query language and its characteristics. Those characteristics display a high degree of data independence, in the sense that the underlying storage structure need not necessarily be known by the user, nor will his transactions be affected by changes in the storage structure or access strategies. Furthermore the formal language is embodied in an homogeneous environment in which the user may define programs and execute algorithms on the results of his queries to satisfy his problem solving needs. The language interface with the Database relies upon Codd's relational data model [1]: its symmetry, and the semantic completeness of its algebra guarantees a friendly interface to the user. The description of the particular implementation of this data model, that is the memory model, is outside the scope of this paper, nevertheless in what follows we will also give a brief sketch of it whenever it is necessary to clarify some of the characteristics of the language.