3. Data base management systems follow particular models (known as database models) to store and manipulate data. A data base model is characterized by: 1. The way it stores data : STRUCTURE 2. The way data in the structure are manipulated: OPERATIONS Database Systems Models

5. MAJOR DATABASE MODELS : HIERARCHICAL MODEL NETWORK MODEL RELATIONAL MODEL OBJECT ORIENTED MODEL Note: Currently, Relational Model is most popular. Our class will focus on Relational DBMS.

10. Evolution of DB Systems

11. Hierarchical Database Model

12. DEPARTMENT EMPLOYEE PROJECT SKILL DEPENDENT EQUIPMENT Hierarchical Database Model

17. DEPARTMENT EMPLOYEE PROJECT DEPENDENT EQUIPMENT Network Database Model

22. Relational Database definition All information must be represented explicitly in one and only one way: as values in tables and each & every datum in the database must be accessible by specifying a table name, a column name, and a primary key.

27. TABLE (Relation) Primary Key Degree Attributes Cardinality Tuples Islamabad 25 Nasir S5 Lahore 34 Abdul S4 Karachi 40 Azmat S3 Islamabad 10 Zafar S2 Lahore 20 Kamran S1 City Quantity SName SCode Supplier Domain Domain

28. Member of a relation type (set / table). All attribute names must be unique within a table / relation. A set of all possible values that can be attain by an attribute. Values currently contained in an attribute. Number of attributes in a relation / table. Rows in a table / relation. Number of tuples in a relation / table. Tuples: Relation / Table Degree: Attribute Value Set: Attribute Domain: Attribute Name: Attribute (field): Cardinality:

30. Database Schema The description of the database is called database schema. A database schema is describe during database design and not expected to change frequently. Schema Diagram Displayed schema is called schema diagram. Each object in schema is called a schema construct.

31. Database instance (occurrence or state) The data in a database at a particular moment of time. Intension & Extension The schema is sometimes called the intension and a database instance is called an extension of the schema.

32. Relational Database Concepts Field Record Table Classical W.A. Mozart Requiem 3 Jazz John Coltrane Blue Train 2 Rock Pink Floyd The Wall 1 Genre Artist Title CD_ID

33. Basic component of a Relation

35. Examples of Attribute Domains

36. Alternative Terminology for Relational Model

39. Difference between a DBMS and RDBMS RDBMS normally use a 4GL DBMS normally use 3GL Examples are ORACLE, INGRESS, SQL Server 2000 etc Examples are dBase, FOXBASE, etc Uses concept of table Uses concept of a file Platform used can be any DOS, UNIX,VAX,VMS, etc Platform used is normally DOS Hardware and Software requirements are High Hardware and Software requirements are minimum Speed of operation is very Fast Speed of operation is very slow It is based on the concept Of relationships The concepts of relationships is missing in a DBMS. If it exits it is very less. RDBMS DBMS

40. Popular DBMS In The Market Sybase SQL Anywhere Informix Dynamic Server Borland Interbase

42. Typical Components Software Users Data DBMS Database “ How” to get Application Programs “ What” to get End users interact Application Programmers develop Database Designers design maintain Database Administrators

44. Overall System Structure

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47. Data about various entities and their relationships are stored in a series of logical tables (also known as relations). A relation is a two-dimensional table with certain imposed restrictions: 1. Each Row is unique: No duplicate row 2. Entries in any column have the same domain. 3. Each column has a unique name 4. Order of the columns or rows is irrelevant 5. Each entry in the table is single valued: No group item, repeating group, or array is allowed. PRINCIPLES OF RELATIONAL MODEL Note: A domain is the set of all possible values an attribute may assume. Example: Domain of Major= (Acct, Mktg, Mgmt, ISOM, Fina)