1. intro
- 1. Introduction to Database Management System
- 2. The Traditional Approach To Data Management – Create new files for each application – Data redundancy – Data integrity
- 3. Disadvantages of File Processing • Program-Data Dependence – All programs maintain metadata for each file they use • Data Redundancy (Duplication of data) – Different systems/programs have separate copies of the same data • Limited Data Sharing – No centralized control of data • Lengthy Development Times – Programmers must design their own file formats • Excessive Program Maintenance – 80% of of information systems budget
- 4. Components of the database environment
- 5. Components of the Database Environment • CASE Tools – computer-aided software engineering • Repository – centralized storehouse of metadata • Database Management System (DBMS) – software for managing the database • Database – storehouse of the data • Application Programs – software using the data • User Interface – text and graphical displays to users • Data Administrators – personnel responsible for maintaining the database • System Developers – personnel responsible for designing databases and software • End Users – people who use the applications and databases
- 6. Disadvantages of DBMS • Databases used in enterprises may involve additional risks as compared to a conventional data processing system in some areas • Confidential, Privacy and Security : When information is centralized and is made available to users from remote locations, there is a possibility of unauthorized users accessing sensitive information. • It is necessary to take technical, administrative and legal measures.
- 7. Disadvantages of DBMS • Data Quality : Since database is accessible to users remotely, adequate controls are needed to control users updating data and to control data quality. • With increased number of users accessing directly, there is an opportunity for users to damage data.Unless there are suitable controls, the data quality may be compromised. • Data Integrity : Since a large number of users cloud be using a database concurrently, technical safeguards are necessary to ensure that data remain correct during operation.
- 9. Overall System Structure • A database system is partitioned into modules which handles different responsibilities of over all system. The functional components of a database system are Query processor Component Storage manager component
- 10. Query Processor Component • DML Compiler : It translates DML statements into a lower level instructions that the query evaluation engine understands • Embedded DML precompiler : It converts DML statements embedded in an application program into normal procedure calls in the host language. • DDL Interpreter : It interprets DDL statements and records them in a set of tables • Query evaluation engine : It executes lower level instructions generated by the DML compiler
- 11. Storage manager component • It is an Interface between the data stored in the database and the application programs and queries submitted to the system. • Authorization and Integrity manager : It tests for satisfaction of integrity constraints and checks the authority of users to access data. • Transaction Manager : It ensures concurrent transaction executions processed without conflicting. • File manager : It manages the allocation of space on disk and the data structures used to represent information. • Buffer manager : Which is responsible for fetching data from disk storage into main memory.
- 12. Application Architectures Two-tier architecture: E.g. client programs using ODBC/JDBC to communicate with a database Three-tier architecture: E.g. web-based applications, and applications built using “middleware”