1. 1 Introduction An organization's survival relies on decisions made by management An organization's survival relies on decisions made by management To make decisions, managers rely on good, timely, and relevant information. To make decisions, managers rely on good, timely, and relevant information. Information is obtained by === Information is obtained by === As data are the building blocks of information, quality of data is critical to quality of information, decision-making, and organizational well being. As data are the building blocks of information, quality of data is critical to quality of information, decision-making, and organizational well being.

2. 2 Data and Information Data Data Raw Facts, without any meaning Raw Facts, without any meaning Managed by DBMS Managed by DBMS Information Information Has meaning, created by processing data. Has meaning, created by processing data. Combined with rules, produces knowledge Combined with rules, produces knowledge Created and Reported by Management Information System. Created and Reported by Management Information System.

3. 3 Database a database is a structured collection of data and metadata that enable computer programs to find answers to queries a database is a structured collection of data and metadata that enable computer programs to find answers to queries Data retrieved in answer to these queries assume the form of information useful for decision making Data retrieved in answer to these queries assume the form of information useful for decision making

4. 4 Qualification for Database Most professionals consider collection of data as database only if it: Most professionals consider collection of data as database only if it: is managed to ensure its integrity and quality is managed to ensure its integrity and quality allows shared access by a community of users allows shared access by a community of users has a schema has a schema supports a query language. supports a query language.

5. 5 DBMS Complex set of software program that controls the organization, storage, management, and retrieval of data from a database Complex set of software program that controls the organization, storage, management, and retrieval of data from a database Accepts requests for data from application program and instructs operating system to transfer the appropriate data Accepts requests for data from application program and instructs operating system to transfer the appropriate data Enables addition of new categories of data to the database without disruption to the existing system Enables addition of new categories of data to the database without disruption to the existing system

6. 6 Components of DBMS Modeling language to define schema of each database hosted according to the data model Modeling language to define schema of each database hosted according to the data model Data structures optimized to deal with huge data stored on a permanent data storage device Data structures optimized to deal with huge data stored on a permanent data storage device Query language and report writer Query language and report writer Transaction mechanism to ensure data integrity Transaction mechanism to ensure data integrity

7. 7 Importance of DBMS Facilitates effective & efficient data management Facilitates effective & efficient data management Facilitates information retrieval with ad hoc queries Facilitates information retrieval with ad hoc queries Facilitates access to large, organized data Facilitates access to large, organized data Promotes integrated view of an organization’s operations Promotes integrated view of an organization’s operations Reduces chance of data inconsistency Reduces chance of data inconsistency

8. 8 Functions of DBMS Manages data dictionary Manages data dictionary Manages data storage Manages data storage Responsible for data transformation & presentation Responsible for data transformation & presentation Manages data integrity & security Manages data integrity & security Controls multi-user access Controls multi-user access Manages backup & recovery Manages backup & recovery Manages database language & API Manages database language & API Manages database communication interface Manages database communication interface Manages video Manages video

9. 9 Evolution Databases were first created to perform clerical tasks Databases were first created to perform clerical tasks Later, they were designed for requesting information Later, they were designed for requesting information These needs were met through File Systems These needs were met through File Systems

10. 10 File Systems File systems may be considered as less powerful database technology File systems may be considered as less powerful database technology Data organized according to expected use Data organized according to expected use Manual files systems were computerized by data Processing specialists Manual files systems were computerized by data Processing specialists

11. 11 File System Terminology Field - Group of characters with specific meaning Field - Group of characters with specific meaning Record - Logically connected fields describing a person, place, or thing Record - Logically connected fields describing a person, place, or thing File - Collection of related records File - Collection of related records E.g. Telephone Directory E.g. Telephone Directory

12. 12 Problems with File System Extensive use of 3GL Extensive use of 3GL No support for ad hoc query No support for ad hoc query Results in islands of Information Results in islands of Information Changing data characteristic requires modifying data access programs (data dependence) Changing data characteristic requires modifying data access programs (data dependence) Changing file structure requires modifying related programs (structural dependence) Changing file structure requires modifying related programs (structural dependence)

13. 13 Problems with File System (Contd) No standard for field nomenclature No standard for field nomenclature E.g. SSN, Socnum, Empid) E.g. SSN, Socnum, Empid) Data Redundancy Data Redundancy Conflicting versions of same data Conflicting versions of same data Results of uncontrolled data redundancy Results of uncontrolled data redundancy Data anomalies Data anomalies Data inconsistency Data inconsistency

14. 14 Database Systems Logically related data stored in a single repository Logically related data stored in a single repository Elimination of inconsistency, data anomalies, data dependence, & structural dependence Elimination of inconsistency, data anomalies, data dependence, & structural dependence Storage of data structures, relationships, and access paths Storage of data structures, relationships, and access paths

15. 15 Database vs. File Systems Figure 1.6

16. 16 Database System Environment Figure 1.7

17. 17 Types of Database Systems Single-user vs. multiple-user database Single-user vs. multiple-user database Desktop, Workgroup, Enterprise Desktop, Workgroup, Enterprise Central vs. Distributed use Central vs. Distributed use Productional vs. Transactional Productional vs. Transactional Decision Support vs. Data Warehouse Decision Support vs. Data Warehouse