Module Title? DBMS Introduction to Database Management System

Module Title? DBMS Data vs. Information  Data  Raw facts, text, graphics, images, sound and video segments that have meaning in the user’s environment  Information  Data that have been processed in such a way as to increase the knowledge of the person who uses the data  Data are raw facts. Information is processed data to reveal the meaning behind the facts.

Module Title? DBMS Traditional Approach  Systems used files to store information  Separate systems - Separate files and programs for each application  E.g. Payroll files, Personnel files, Accounts files etc.

Module Title? DBMS Example of file system

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data)

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data) l wasteful of space (storage)

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data) l wasteful of space (storage) l update inefficiencies

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data) l wasteful of space (storage) l update inefficiencies Ù (when a teacher moves to a new address, or changes her name, the teacher's "record" must be changed each place it is stored)

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data) l wasteful of space (storage) l update inefficiencies Ù (when a teacher moves to a new address, or changes her name, the teacher's "record" must be changed each place it is stored) l data inconsistency (different addresses for the same teacher in different files)

Module Title? DBMS Some Problems with Traditional File Processing Systems l Redundancy (duplication of data) l wasteful of space (storage) l update inefficiencies Ù (when a teacher moves to a new address, or changes her name, the teacher's "record" must be changed each place it is stored) l data inconsistency (different addresses for the same teacher in different files)

Module Title? DBMS LIMITATIONS OF FILE-BASED  SEPARATION AND ISOLATION  Payroll Office files has the teachers' names and id's and departments  Principal's Office Files has teacher’s names, the current salary scale and date this salary scale became effective  Asst. Principal's Office files has seminar topics for each teacher  PROGRAM & DATA DEPENDENCE  The Payroll Department has written some lengthy Pascal programs to access their files and perform queries and reports.  The Personnel Department has written some C programs to access their files and perform queries and reports.

Module Title? DBMS Database Approach  Build a SINGLE pool of interrelated files, rather than SEPARATE collection of files.  (This is an INFORMAL description of a database).

Module Title? DBMS DATABASE  A COLLECTION OF SELF-DESCRIBING AND INTEGRATED,ORGANISED DATA (Kroenke's Definition of a Database)

Module Title? DBMS DATABASE MANAGEMENT SYSTEM (DBMS)  A collection of Programs that enables you to Store, modify, and extract (access) information from a database.  Provides the interface between the user and the data in the database  Allocates storage to data and maintains indices so that any required data can be retrieved.  Protects data against corruption  Provides recovery and restart facilities after a hardware or software failure.

Module Title? DBMS Database System:  The DBMS software together with the data itself. Sometimes, the applications are also included. ApplicationApplication DBMSDBMS data catalog database

Module Title? DBMS Database vs. File Systems

Module Title? DBMS DATABASE MANAGEMENT SYSTEM (DBMS)  The following are examples of Database Applications:  Banking: all transactions  Airlines: reservations, schedules  Universities: registration, grades  Sales: customers, products, purchases  Manufacturing: production, inventory, orders, supply chain  Human resources: employee records, salaries, tax deductions

Module Title? DBMS Different DBMS Software ORACLE ACCESS SQL SERVER IBM DB2 Sybase SAP DB PostgreSQL MySQL MS SQL Server,... DATABASE MANAGEMENT SYSTEM (DBMS)

Module Title? DBMS Advantages of Database Approach  Controlling redundancy in data storage and in development and maintenance efforts.  Sharing of data among multiple users.  Restricting unauthorized access to data.  Greater consistency of data  Enforcing integrity constraints on the database.  Providing backup and recovery services.  Availability of up-to-date information.

Module Title? DBMS Database System Environment Application Programs/ Queries DBMS Software Software to Process Queries/ Program Software to Access Stored Data Stored Database Stored Data Definition (Meta-Data)

Module Title? DBMS Data Models  Data Model is a set of concepts that can be used to describe the structure of a database  data types, relationships, and constraints  Data Model Examples:  Relational - describes database structure as tables  Network - describes database structure as a network  Object Oriented - describes database structure as objects

Module Title? DBMS HISTORY OF DATABASE SYSTEMS FIRST GENERATION _ HIERARCHICAL MODEL INFORMATION MANAGEMENT SYSTEM (IMS) –NETWORK MODEL CONFERENCE ON DATA SYSTEM LANGUAGES (CODASYL) DATA BASE TASK GROUP (DBTG) SECOND GENERATION –RELATIONAL MODEL E. F. CODD DB2, ORACLE THIRD GENERATION –EXTENDED RELATIONAL DATA MODEL OR OBJECT-RELATIONAL DATA MODEL –OBJECTED-ORIENTED DATA MODEL

Module Title? DBMS Schema Architecture  Database Schema: The description of a database. It Includes descriptions of the database structure and the constraints that should hold on the database.

Module Title? DBMS The three-schema architecture.

Module Title? DBMS The three-schema architecture.  External schema describes part of a database that a particular user or users are interested in.  Using the relational model, these are views  Conceptual schema describes the structure of he whole database for a community of users.  Using the relational model, these are tables  Internal schema describes the physical storage structure of the database.  These are not tables, this is the data as stored by the DBMS.

Module Title? DBMS ROLES IN DATABASE ENVIRONMENT (USERS)  DATA ADMINISTRATOR  Implements the database  APPLICATION PROGRAMMER  Interact with the database through high level programming  END-USER  Interacts and uses the database

Module Title? DBMS Data Dictionary

Module Title? DBMS Database Languages  Data Definition Language (DDL)  Used to define the conceptual and internal schemas  Data Manipulation Language (DML)  Used to describe operations on the instances of a database  Procedural DML (how) vs. declarative DML (what) e.g., Relational Algebrae.g., SQL  Note, SQL includes a DML and a DDL in one!

Module Title? DBMS Database Languages  DCL Data Control Language. [Grant, Revoke commands (oracle)]  TCL [Transaction control Language] [Commit, Rollback, savepoint commands (oracle)]

Module Title? DBMS  Classification of DBMS based on the data model used:  Relational DBMS  Network DBMS  Hierarchical DBMS  Object-oriented DBMS  Object-relational DBMS

Module Title? DBMS  Classification of DBMS based on the number of users:  Single-user (typically used with micro- computers)  Multi-user (most DBMSs).  Classification of DBMS based on the number of sites:  Centralized (uses a single computer with one database)  Distributed (uses multiple computers, multiple databases)