Database Reference
In-Depth Information
Relational Calculus
This chapter discusses relational calculus as an alternate way of manipulating relations in
a database. The partial college database, introduced in the previous chapter (Figures 7-1
and 7-2) will be used as a frame or reference. It must be constantly borne in mind that
relational algebra and relational calculus are mutual equivalents; most DBMS suites will
implement one or the other, or aspects of both, depending on what is convenient to the
developers. The chapter proceeds under the following subtopics:
Introduction
Calculus Notations and Illustrations
Quantifiers, Free and Bound Variables
Substitution Rule and Standardization Rules
Query Optimization
Domain Related Calculus
Summary and Concluding Remarks
8.1 Introduction
In relational calculus, we simply specify what is required, not how to obtain the required
relation(s). Relational algebra, on the other hand, provides a collection of explicit
operations in SELECT, JOIN, PROJECT etc., which can be used to tell the system how to
derive desired relation(s).
Example 1: Suppose that we are interested in obtaining a list of program names and
associated course names for the Bachelor of Science in MIS.
 
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