1. CIS/SUSL1 Fundamentals of DBMS S.V. Priyan Head/Department of Computing & Information Systems

2. CIS/SUSL2 References Read the link given in the following URL http://www.sab.ac.lk/app/courses/dep-it-first.htm

3. CIS/SUSL3 Evaluation Methods As in the board

4. CIS/SUSL4 Practical Weekly Laboratory Practical

5. CIS/SUSL5 Today’s Topic File systems vs. Database Management Systems (DBMS) Characteristics Actors Workers Behind the Scene DBMS and its Advantages

6. CIS/SUSL6 Introduction Data –Are known facts that can be recorded and that have an implicit meaning Database –is a collection of related data E.g.:- names addresses TP numbers

7. CIS/SUSL7 DBMS Definition –is a collection of programs that enables users to create and maintain database. Thus, DBMS is a software system that facilitates the processes of defining, constructing and manipulating databases for various applications E.g.: Oracle 9i

8. CIS/SUSL8 Defining a database involves specifying the data types, structures and constraints for the data to be stored. Construction of a database is the process of storing the data itself on some storage medium that is controlled by the DBMS. Manipulation of a database includes functions for querying, retrieving, updating and report generating. DBMS

9. CIS/SUSL9 Files vs. DBMS Application must stage large datasets between main memory and secondary storage (e.g., buffering, page-oriented access, 32-bit addressing, etc.) Special code for different queries Must protect data from inconsistency due to multiple concurrent users Crash recovery Security and access control

10. CIS/SUSL10 Why Use a DBMS? Data independence and efficient access. Reduced application development time. Data integrity and security. Uniform data administration. Concurrent access, recovery from crashes.

11. CIS/SUSL11 Requirements modeling (conceptual) –Decide what entities should be part of the application and how they are related Schema design and database creation –Decide on a database schema –Define the schema to the DBMS –Load data into the database Access to data –Use a database language –Write database application programs –Use database application programs How to Use a DBMS

12. CIS/SUSL12 Two views derived from the database

13. CIS/SUSL13 Actors For a small personal database, the list of addresses discussed, one person typically defines, constructs, and manipulates the database, and there is no sharing. However, in large organizations, many people are involved in the design, use, and maintenance of a large database with hundreds of users Can also called as “workers behind the scene”

14. CIS/SUSL14 Large database many persons are involved in the design, use, and maintenance –Database Administrators –The primary resource is the database itself and the secondary resource is the DMBS and related software –Administering these resources is done by DBA –Database Designer –Responsible for identifying the data to be stored –Choosing appropriate structures to represent and store data. –Should be done before the database is actually implemented and populated with data. –End Users –These are the people whose jobs require access to the database for querying, updating and generating reports. Actors

15. CIS/SUSL15 Casual end users –Access the database occasionally, but the may require different information each time. Naive or parametric end users –Are querying and updating the database using standard types of queries and updates that have been carefully programmed and test. This process is called canned transaction. Sophisticated end users –Are the people who thoroughly familiar with the facilities of the DBMS to implement their applications to meet their complex requirements. These end users include engineers, scientists, business analysts, and others. Stand-alone users –Maintain personal databases by using ready-made program packages that provide menu or graphic based interfaces that is easy to use. Actors

16. CIS/SUSL16 System Analysts and Application Programmers (Software Engineers) –System analysts determine the requirements of end users –Application programmers implement these specifications as programs DBMS system designers and implementers –design and implement the DBMS modules and interfaces as a software package Actors

17. CIS/SUSL17 Controlling redundancy –This avoids duplication of data, waste of space And inconsistency of data. Restricting unauthorized access – When multiple users share a database, some of them may not be allowed to access the entire database. Such users must be provided controlled access to the database. DBMS provides security and authorization subsystems to facilitate this. Providing persistent storage for program objects and data structures. –Traditional database systems suffered from the impedance mismatch problem, since the data structures provided by the DBMS were incompatible with the programming languages and data structures. Object oriented database management systems offer data structures compatible with one or more object-oriented languages. Advantages of using a DBMS

18. CIS/SUSL18 Providing multiple user interfaces –Because many users with various levels of technical knowledge use a database, a DBMS should provide a variety of user interfaces. Representing complex relationships among data –A DBMS must have the capability to represent a variety of complex relationships among the data as well as to retrieve and update related data easily and efficiently. Enforcing integrity constraints –Most database applications certain integrity constraints that must hold for the data. A DBMS should provide capabilities for defining and enforcing these constraints. Provide backups and recovery –A DBMS must provide facilities for recovering from hardware or software failure. The backup and recovery subsystems of DBMSs facilitate this. Advantages of using a DBMS

19. CIS/SUSL19 Next Week : Database System Concepts and Architecture Assignment No 1 will be posted