ICS (072)Database Systems Background Review 1 Database Systems Background Review Dr. Muhammad Shafique

ICS (072)Database Systems Background Review 2 Outline Databases and Database Users Database System Concepts and Architecture

ICS (072)Database Systems Background Review 3 Databases and Database Users (1) Database concepts Database A database represents some aspect of the real world A database is a logically coherent collection of data with some inherent meaning. A database is designed, built, and populated with data for a specific purpose. It has an intended group of users and some preconceived applications in which these users are interested. Database Management System A database management system (DBMS) is a collection of programs that enables users to create and maintain a database.

ICS (072)Database Systems Background Review 4 Databases and Database Users (2) Typical DBMS Functionality Define a database Construct or Load the Database Manipulating the database Concurrent Processing and Sharing Other features: Protection or Security measures to prevent unauthorized access “Active” processing to take internal actions on data Presentation and Visualization of data

ICS (072)Database Systems Background Review 5 Databases and Database Users (3)

ICS (072)Database Systems Background Review 6 Databases and Database Users (4) Characteristics of the Database Approach Self-describing nature of a database system Insulation between programs and data Data Abstraction program-data independence Support of multiple views of the data Sharing of data and multi-user transaction processing

ICS (072)Database Systems Background Review 7 Databases and Database Users (5) Database Users Database administrators Database Designers End-users Casual Naïve or Parametric Sophisticated Stand-alone

ICS (072)Database Systems Background Review 8 Databases and Database Users (6) Advantages of Using the Database Approach Controlling redundancy Sharing of data among multiple users Restricting unauthorized access to data Providing persistent storage Providing Storage Structures for efficient Query Processing Providing backup and recovery services Providing multiple interfaces to different classes of users Representing complex relationships among data Enforcing integrity constraints on the database Drawing Inferences and Actions using rules

ICS (072)Database Systems Background Review 9 Databases and Database Users (7) Additional Implications of Using the Database Approach Potential for enforcing standards Reduced application development time Flexibility to change data structures Availability of up-to-date information Economies of scale

ICS (072)Database Systems Background Review 10 Databases and Database Users (8) Historical Development of Database Technology Early Database Applications Hierarchical and Network Models Relational Model based Systems Object-oriented applications Data on the Web and E-commerce Applications

ICS (072)Database Systems Background Review 11 Databases and Database Users (9) Extending Database Capabilities Scientific Applications Image Storage and Management Audio and Video data management Data Mining Spatial data management Time Series and Historical Data Management The above gives rise to new research and development in incorporating new data types, complex data structures, new operations and storage and indexing schemes in database systems.

ICS (072)Database Systems Background Review 12 Database System Concepts and Architecture (1) Data model A collection of concepts that can be used to describe the structure of a database Categories of data models Conceptual (high-level, semantic) data models Logical/Implementation (representational) data models Physical (low-level, internal) data models

ICS (072)Database Systems Background Review 13 Database System Concepts and Architecture (2) Schemas and Instances Database Schema The description of a database is called the database schema, which is specified during database design and is expected not to change frequently Schema Diagram Schema Construct Database Instance The actual data stored in a database at a particular moment in time. Also called database state (or occurrence).

ICS (072)Database Systems Background Review 14 Database System Concepts and Architecture (3) Database Schema Vs. Database State Database State Initial Database State Valid State Distinction The database schema changes very infrequently The database state changes every time the database is updated. Schema is also called intension, whereas state is called extension.

ICS (072)Database Systems Background Review 15 Database System Concepts and Architecture (4) Three-Schema Architecture Internal schema Conceptual schema External schemas Mappings Transformations from one schema level to the other are needed to translate requests and data. Programs refer to an external schema, and are mapped by the DBMS to the internal schema for execution

ICS (072)Database Systems Background Review 16 Database System Concepts and Architecture (5)

ICS (072)Database Systems Background Review 17 Database System Concepts and Architecture (6) Data Independence Logical Data Independence Physical Data Independence DBMS Languages Data Definition Language (DDL) Storage Definition Language (SDL) View Definition Language (VDL) Data Manipulation Language (DML): DML commands (data sublanguage) can be embedded in a general-purpose programming language (host language) DML commands can be applied directly (query language).

ICS (072)Database Systems Background Review 18 Database System Concepts and Architecture (7) DBMS Interfaces Stand-alone query language interfaces Programming interfaces Pre-compiler Approach Procedure (Subroutine) Call Approach User-friendly interfaces Menu-based Forms-based Graphics-based Natural language Speech as Input (?) and Output Web Browser Parametric interfaces Interfaces for the DBA

ICS (072)Database Systems Background Review 19 Database System Concepts and Architecture (8) Database System Utilities Loading data Backing up Reorganizing Performance monitoring Sorting User monitoring Data compression

ICS (072)Database Systems Background Review 20 DBMS Component Modules

ICS (072)Database Systems Background Review 21 Database System Architectures (1) Centralized

ICS (072)Database Systems Background Review 22 Database System Architectures (2) Client-Server (two-tier logical)

ICS (072)Database Systems Background Review 23 Database System Architectures (3) Client-Server (two-tier physical)

ICS (072)Database Systems Background Review 24 Database System Architectures (4) Client-Server (three-tier) Presentation layer Business logic layer Database services layer

ICS (072)Database Systems Background Review 25 References 1.Textbook Chapter 1 2.Textbook Chapter 2

ICS (072)Database Systems Background Review 26 Summary Databases and Database Users Database System Concepts and Architecture