Introduction

1. Introduction • Database integral part of our day to day life • Collection of related database • Database Management System : software managing and controlling access to the database. • Databasesystem : collection of application interracting with database

2. Example of use of database systems A database is accessed when : • Purshasing in a supermarket ( item price) • Purchase using credit cards ( valid cards) • Inquiries about a holliday (flight details) • Make a loan (library) • Rent video ( detail info on each video) • Online bookstore( book details)

3. Sample data

4. Project Identifcation and Selection Project Initiation and Planning Analysis Logical Design Physical Design Implementation Maintenance Dtabase in the dev cycle

5. Database • A repository of data simultaneously used by many users (a shared ressource). • Collection of logically related data. • Description of this data (data dictionary) • BDMS Software interracting with : • Users • Application programs • database

6. BDMS Software interracting with : • Users • Application programs • Database DBMS allows users (using a query language): • Insert • Update • Delete • Retrive data from DB

7. Database application programs Computer program that allow users to interact with the DB through DBMS.

8. DBMS environment • Hardware :Computer systems that DBMS and application programs run on. • Software: DBMS,application programs, operating system, network software(if DBMS used over network). • Data ( operational data and meta-data) • Procedures: instruction and rules that govern use of database • People: DB designer, administrators , programmers and end users

9. Database environment

10. DBMS architecture 2 layerarchitecture Client-Server • The clientthat runs the application and the server that handles the database back-end • Multiple usersable to access the DB simultanousely. • Server is processing data while the client for business logic and presentation.

11. 2-Tier Architecture

12. DBMS architecture 3 layer architecture • User Interface layer ( runs on the user´s client) • Business logic (middle layer) and data processing layer. Runs on a server called ”application server”. • DBMS ( store data ) , may run on a separate server called ”database server”

14. 3 layer architecture advantages • Thin client (less hardware) , client only handling presentation logic.This means a little communication needed between the client(browser) and the middle tier. • Separating the core business logic from the database functions • Modularity : Easy to modify or replace one tier without affecting the other tiers • Easier load balancing • Maps quite naturally to the web environment • Security : middle tier protecting the DB. • Scalabale : add as many middle tier as needed

15. Functions of a DBMS • Data storage , retrieval and update • A user-accessible Catalog • Hold data about the structure of database , users , applications and so on • Transaction support • Ensure that all the updates are made or that none of them are made • Concurrency control services • Enable many users to access shared data concurrently • Recovery services • When transaction fails, DB revovered to a consistent state

16. Functions of a DBMS • Autorization services • Only special part could have access to info • Support for data communication • Terminal at remote locations can communicate with host of DBMS through network • Integrity Services • Stored data are consistent and correct • Services to promote Data Independence • Utility Services • Utility program help manage the DB effectively

17. Advantages of DBMS • Control of data redundancy (duplication) • Eliminate redundency where possible , • Data consistency • Data stored in more than once , system can ensure that all copies of the data are kept consistent • Sharing of data • By all authorized users • Improved data integrity • Rules that DB is not permitted to violate • User define data and DBMS enforce it • Improved maintenance through data independence • Make application immune to changes in data description