CS632 Notes on Relational Query Languages I
نویسنده
چکیده
We begin with a data domain D, an (infinite) set from which all data values will be taken. Thus, while it is conventional to use distinct types for distinct fields of a data record (e.g. the SSNO field is an integer, while the NAME field is a character string), we assume the single domain D is rich enough to represent any values we might be interested in. None of the technical results below is afffected by this decision, and it simplifies some of the arguments.
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تاریخ انتشار 2003