Fundamentals of database systems / Ramez Elmasri, Shamkant B. Navathe.—6th ed. important aspects of database systems and applications, and related. Fundamentals of database systems / Ramez Elmasri, Shamkant B. Navathe. course in database systems at the junior, senior, or graduate level, and as a. Fundamentals of Database Systems . Chapter 2: Database System Concepts and Architecture. DBMS Architecture and Data Independence.
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Library of Congress Cataloging-in-Publication Data Elmasri, Ramez. Fundamentals of database systems / Ramez Elmasri, Shamkant B. Navathe.—6th ed. p. cm. Fundamentals of Database Systems, 7th Edition. Ramez Elmasri, University of Texas at Arlington. Shamkant B. Navathe, University of Texas at Arlington. Fundamentals of database systems / Ramez Elmasri, Shamkant B. used as a textbook for a one- or two-semester course in database systems at the junior.
Navathe, Addison-Wesley Pearson, Carrick and D. Levine, McGraw-Hill, Navathe, Addison-Wesley, Modeling Biomedical Data, with F.
Ji and J. Sidhu and J. Chen editors , Artech House Publishing, Fundamentals of Database Systems, with S.
The third edition is scheduled for publication in July Addison-Wesley. Elmasri has served on the program committees of many international conferences, and has presented tutorials and keynote talks at a number of international conferences.
He has received the Robert Q. Shamkant Navathe is a professor and the head of the database research group at the College of Computing, Georgia Institute of Technology, Atlanta. He is well-known for his work on database modeling, database conversion, database design, distributed database allocation, and database integration. He is an author of the book, Fundamentals of Database Systems, with R. Elmasri Addison Wesley which is currently the leading database text-book worldwide.
Hm... Are You a Human?
Impossible, you say? Well, yes, unless the program has the ability to access a description of the file's record layout i.
This illustrates the power of metadata, i. Multiple Views of Data: Different users e. For example, from the point of view of a Bursar's Office employee, student data does not include anything about which courses were taken or which grades were earned. This is an example of a subset view. As another example, a Registrar's Office employee might think that GPA is a field of data in each student's record.
In reality, the underlying database might calculate that value each time it is needed. This is called virtual or derived data.
A view designed for an academic advisor might give the appearance that the data is structured to point out the prerequisites of each course. A good DBMS has facilities for defining multiple views.
This is not only convenient for users, but also addresses security issues of data access. The same is true for multi-user DBMS's. Arising from this is the need for concurrency control, which is supposed to ensure that several users trying to update the same data do so in a "controlled" manner so that the results of the updates are as though they were done in some sequential order rather than interleaved, which could result in data being incorrect.
This gives rise to the concept of a transaction, which is a process that makes one or more accesses to a database and which must have the appearance of executing in isolation from all other transactions even ones that access the same data at the "same time" and of being atomic in the sense that, if the system crashes in the middle of its execution, the database contents must be as though it did not execute at all.
Applications such as airline reservation systems are known as online transaction processing applications.
Database Administrator DBA : This is the chief administrator, who oversees and manages the database system including the data and software.
In large organizations, the DBA might have a support staff. Database Designers: They are responsible for identifying the data to be stored and for choosing an appropriate way to organize it.
ISBN 13: 9780321369574
They also define views for different categories of users. The final design must be able to support the requirements of all the user sub-groups. End Users: These are persons who access the database for querying, updating, and report generation.
They are main reason for database's existence!
Casual end users: use database occasionally, needing different information each time; use query language to specify their requests; typically middle- or high-level managers. Sophisticated end users: engineers, scientists, business analysts who implement their own applications to meet their complex needs.
Stand-alone users: Use "personal" databases, possibly employing a special-purpose e.
If You're an Educator
System Analysts, Application Programmers, Software Engineers: System Analysts: determine needs of end users, especially naive and parametric users, and develop specifications for canned transactions that meet these needs. Application Programmers: Implement, test, document, and maintain programs that satisfy the specifications mentioned above.
On the other hand, redundancy can be used to improve performance of queries. Indexes, for example, are entirely redundant, but help the DBMS in processing queries more quickly.
Another example of using redundancy to improve performance is to store an "extra" field in order to avoid the need to access other tables as when doing a JOIN, for example.
A DBMS should provide the capability to automatically enforce the rule that no inconsistencies are introduced when data is updated.
Figure 1.Permitting Inferencing and Actions Via Rules: In a deductive database system, one may specify declarative rules that allow the database to infer new data! An Aside: data vs. Referential integrity constraints are shown as directed arcs in Figure 6.
Modeling Biomedical Data, with F. Robert Q. Elmasri has over 70 refereed publications in journals and conference proceedings.
Many of these constraints are now part of the SQL standards. He holds M. To summarize: a database has some source i.