Database Reference
In-Depth Information
Figure 7-2.
Sample Data for a Cross-section of a College/University Database[Showing
only attributes relevant to the examples discussed] (continued)
In the interest of clarity, two commonly used notations have been adopted, both
with slight modifications. They are the Ullman notation [Garcia-Molina, 2002] and the
Date notation [Date, 2004]. Bear in mind however, that the syntactical implementation of
relational algebra will vary from one product to another. What is important therefore, is
that you understand the concepts discussed. The BNF (Backus-Naur Form) conventions
shown in Figure
7-3
will be assumed. Additionally, several of the examples will
contain clarifying comments that conform to how comments are made in the C-based
programming languages (e.g. // this is a comment, /* and so is this */). Use of the BNF
notation and C-based comments will continue through chapter 8 as well.
