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Authors: Bradley, J.
Keywords: Computer Science
Issue Date: 1-Feb-1984
Abstract: The original relational languages such as DSL Alpha used the basic universal and existential quantifiers in the traditional manner of mathematical logic, which is not the way in which they are used in natural languages. When DSL Alpha proved too difficult for use in a data base language SQL was developed. SQL uses special constructs to avoid the quantifiers of DSL Alpha but is otherwise similar. SQL is heavily supported by IBM and other vendors and is becoming the standard non procedural data base language. Although SQL is clearly easier to use than DSL Alpha, because it continues to use the equivalent of the basic quantifiers in the traditional manner of mathematical logic, for more complex retrievals either an SQL expression is difficult and contrived or is not possible. SQL/N permits the basic quantifiers of DSL Alpha but uses them in the much simpler manner of natural language. In addition it permits the use of the whole range of natural quantifiers. The result is that SQL/N expressions mirror their natural language counterparts and are simpler and more concise than SQL expressions. SQL/N is also upward compatible with SQL so that simple SQL and SQL/N expressions are identical. SQL/N can handle all known kinds of associations easily and permits the use of natural quantifiers with them. In this tutorial we deal only with the common one to many associations.
Appears in Collections:Bradley, James

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