Database_System_Concepts_(Instructor's_Manual).pdf

Chapter 1 provides a general overview of the nature and purpose of database sys-
tems. The most important concept in this chapter is that database systems allow data
to be treated at a high level of abstraction. Thus, database systems differ significantly
from the file systems and general purpose programming environments with which
students are already familiar. Another important aspect of the chapter is to provide
motivation for the use of database systems as opposed to application programs built
on top of file systems. Thus, the chapter motivates what the student will be studying
in the rest of the course.
The idea of abstraction in database systems deserves emphasis throughout, not
just in discussion of Section 1.3. The overview of the structure of databases, starting
from Section 1.4 is, of necessity, rather brief, and is meant only to give the student

a rough idea of some of the concepts. The student may not initially be able to fully
appreciate the concepts described here, but should be able to do so by the end of the
course.
The specifics of the E-R , relational, and object-oriented models are covered in later
chapters. These models can be used in Chapter 1 to reinforce the concept of abstrac-
tion, with syntactic details deferred to later in the course.
If students have already had a course in operating systems, it is worthwhile to
point out how the OSand DBMS are related. It is useful also to differentiate between
concurrency as it is taught in operating systems courses (with an orientation towards
files, processes, and physical resources) and database concurrency control (with an
orientation towards granularity finer than the file level, recoverable transactions, and
resources accessed associatively rather than physically). If students are familiar with
a particular operating system, that OS’s approach to concurrent file access may be
used for illustration.