Overview Relational Database and SQL Session 2 Matakuliah: Web Database Tahun: 2008

2 Last Session Review:Web Database DefinitionWeb Application ExampleInfluence of Web Database to OrganizationWeb Enhanced DatabaseDatabase Enhanced WebWhen To Use Web Database

3 Agenda:Overview Database and DBMSAdvantages of DBMSDisadvantages of DBMSOverview Relational Database Overview SQL Data Definition Language Data Manipulation Language

4 Objective: Student understand about Database, DBMS, Relational Database, SQL, DDL and DMLStudents could demonstrate their ability in SQL, DDL and DML

5 Overview Database and DBMS What is a Database? – Shared collection of logically related data (and a description of the data) design to meet the information needs of an organization – Usually refer specially to the data that is stored on computers – System catalog (metadata) provides description of data to enable program-data independance – Logically related data comprises entities, attributes, and relationships of an organization’s information – History of Database System: First Generation – Hierarchical and Network Second Generation – Relational Third Generation – Object Relational – Object-Oriented

6 Overview Database and DBMS (cont.) What is a Database Management System (DBMS)? – A software system that enables users to define, create, and maintain the database and that provides controlled access to this database DBMS Facilities: – Define Database, usually throught Data Definition Language – Insert, update, delete and retrieve data, usually throught Data Manipulation Language – Control Access to Database – Recovery Control System – User-accesible Catalog

7 Advantages of DBMS Control of data redudancy Data consistency More information from the same amount of data Sharing of Data Improved data Integrity Improved Security Enforcement of Standard Economy of Scale Balanced conflicting requirements Improved data accessibility and responsiveness Increased productivity Improved maintenance through data independence Increased concurrency Improved backup and recovery services

8 Disadvantages of DBMS Complexity Size Cost of DBMS Additional Hardware cost Cost of conversion Performance Higher Impact of failure

9 Overview Relational Database What is a Relational Database? – It is a body of persistent information stored in two-dimensional tables (by a computer program), where the data survives the terminations of a program or user session that created it. – First published in 1970, mostly used this days – A collection of normalized relations with discinct relation name Relational Database Advantages: – Logical – Simplicity – Mathematical rigour – Set-Oriented

10 Overview Relational Database (cont.) Relational Data Structure – Table – Attribute – Relationship – Domain – Keys: Superkey Primary Key Foreign Key – Integrity: Entity Integrity Referential Integrity

11 Overview SQL SQL is a language oriented specifically around relational databases. Forms of SQL: – Interactive SQL – Static SQL – Dynamic SQL The Subdivisions of SQL: – DDL (Data Definition Language) – DML (Data Manipulation Language) – DCL (Data Control Language) Various Types of Data (datatype) can be divided into the following categories: – Text – Numeric – Datetime – Binary, etc

12 Data Definition Language (DDL) Allow DBA or User to describe and name database, tables, attibutes, and relationships required (plus any assosiated integrity and security constraints) Example: – Creating Database – Modifiying Database – Creating, Changing and Dropping Table and Constraints

13 Data Manipulation Language (DML) Provide basic data manipulation operations on data held in the database Example: – Retrieve (Select) data – Insert Data – Update Data – Delete Data

14 Data Manipulation Language (DML) Provide basic data manipulation operations on data held in the database Example: – Retrieve (Select) data – Insert Data – Update Data – Delete Data

15 Summary DBMS is software system that enable user to create, maintain and control Database. DBMS has advatages and disadvantages. Relational Database is mostly and commonly used today. SQL is used to create and maintain DBMS

16 Next Session:Web Basic ConceptHow to put information on WebDynamic Web pagesNew Development of Web

17 End of Overview Relational Database and SQL Thank you