Database Database Users Introduction Database are very much

Database & Database Users

Introduction • Database are very much essential in modern society Several activities interaction with database everyday. Traditional database applications store and access the textual or numeric types New media technology has evolved to support different databases Multimedia Database Geographical Information System (GIS) Databases also provide a platform for analysing the data for support decisions Warehouse OLAP There are real time databases to store and access data on a real time • What is Database? It is collection of related data. Properties of Database: It represents some aspects of real world – Interaction with Events Logical coherent collection – It can be of any size and complexity Serves specific purposes

Introduction • What is DBMS? It is a collection of programs that enables users to create and maintain a database It provides the facilities to, define, construct, manipulate and sharing of databases • Define The data types, structures, and constraints, which is termed as “meta-data” • Construct The process of storing the data on some storage medium. • Manipulate Querying the database for specific result set Getting the meaning information • Share Allows multiple users and programs to access the database simultaneously • Other Functions – Protecting and Maintaining the Database

Simplified Database Environment

Example • Database is a collection of Data Records • To Define database we have to specify different data elements • Data elements constitutes of data types and actual data • To Construct the database, we need to store the data for each data record • Manipulation involves in querying and updating the database • How do we Design the Database ? Requirements Specification and Analysis Conceptual Design – Deals with “What” Logical Design – Deals with “How” Physical Design – Deals with “How”

Characteristics of Database Approach • Self-Describing Nature of a Database System • Insulation between Programs and Data, and Data Abstraction Program-Data Independence Program-Operation Independence • Support of Multiple Views of the Data • Sharing of Data and Multiuser Transaction Processing Concurrency Control Online Transaction Processing (OLTP) Isolation property Atomicity property

Actors on the Scene • Database Administrators • Database Designers • End Users Casual end users Naive or parametric end users Constantly query Sophisticated end users Engineers, Scientists, BA and others Standalone users • System Analyst and Application Programmer

Workers behind the Scene • DBMS system designers and implementers Design and Implement the DBMS modules and interfaces as a software package. Catalog, Query Language Processing, Interface Processing, Accessing and Buffering data, Controlling Concurrency, Handling Data Recovery and Security • Tool Developers Design and Implement the tools to interface the software package Database Modelling and Design Database System Design, and Improved Performance • Operators and maintenance personnel Responsible for the maintenance of the hardware and software environment for the database system

Advantages of using DBMS Approach • Controlling Redundancy - Storing the same data multiple times Duplication of Effort Storage space Inconsistent Data Normalization Controlled Redundancy – Improves Performance • Restricting Unauthorized Access RBAC – Role Based Access Security and Authorization • Providing Persistent Storage for Program Objects Object Oriented Database Systems Object databases store objects rather than data • Providing Storage Structures & Search Techniques for Efficient Query Processing Efficient Query Execution and Updates – Indexes ( Tree DS/ Hash DS) Buffering or Caching – (Database and OS) Query Processing and Optimization

Advantages of using DBMS Approach • Backup & Recovery • Providing Multiple User Interfaces • Representing Complex relationships among Data • Enforcing Integrity Constraints Data Types Referential Integrity Uniqueness Constraint • Permitting Inferencing and Actions Using Rules Deductive Database Systems – Impose Rules Efficient Query Execution and Updates – Indexes ( Tree DS/ Hash DS) Buffering or Caching – (Database and OS) Query Processing and Optimization • Additional Implications Potential for Enforcing Standards Reduced Application Development Time Flexibility Availability of Up-to-Date Information Economies of Scale

Brief History of Database Application • Hierarchical and Network Systems Lack of Data Abstraction and Program-Data Independence Programming Language Interfaces • Providing Data Abstraction and Application Flexibility Separate the Physical Storage of data from its conceptual representation High Level Query Language • Object Oriented Applications • Interchanging Data on the Web for E-Commerce Using XML • Extending Database Capabilities Scientific applications Storage and retrieval of images, video clips Data mining applications Spatial Applications Time series applications

When not to use DBMS • Overhead cost of using DBMS High Initial investment in Hardware, Software and Training Generality that DBMS provides to define and process data Overhead for providing security, concurrency control, recovery, and integrity functions • When not to use DBMS Simple, well-defined database applications that are not expected to change at all Stringent, real-time requirements for some application programs that may not be met because of DBMS overhead Embedded systems with limited storage capacity No multiple-user access to data

Database System Concepts and Architecture • Evolution from monolithic system to tightly integrated system. • Client/Server DBMS architecture - Functionality is distributed between two types of modules Client Runs on a user workstation Application Programs and User Interfaces that access the database Server Handles data storage, access, search, and other functions

Data Models, Schemas, and Instances • Data Abstraction Suppression of details of data organization and storage Users can perceive data at their preferred level of details • Data Model Collection of concepts that can be used to describe the structure of a database Logical Structure of Database • Categories of Data Model High-level or Conceptual Data Model Low-Level or Physical Data Model Representational Data Model

Data Models • Conceptual Data Models An entity represents a real-world object or concept An attribute represents some property of interest A relationship among two or more entities represents an association among the entities • Representational Data Model Represents data by using record structures • Physical data models How data is stored as files in the computer by representing information such as record formats, record orderings, and access paths

Schemas, Instances, and Database State • Database Schema – Description of Database Unexpected to change • Instance Database at a particular moment in time

Three Schema Architecture & Data Independence • Suffices Three characteristics of Database Approach • Three Schema Architecture Internal Level - Physical storage structure of the database Conceptual Level External or View level • The processes of transforming requests and results between levels are called mapping • Data Independence Logical Data Independence Physical Data Independence

Database Languages and Interfaces • Data Definition Language (DDL) – DBA and Database Designer It defines the database schema and its constraints • Storage Definition Language (SDL) • View Definition Language (VDL) • Data Manipulation Language High Level Low Level – ( Record at a time)

Database Languages and Interfaces • Interfaces are the means to connect and access the database • Menu Based Interfaces • Form Based Interfaces • Natural Language Keyword-based querying • Speech Input and Output • Interfaces for Parametric Users • Interfaces for the DBA

Centralized and Client-Server Architectures for DBMS • Centralized DBMSs Architecture • Client-Server Architecture

Centralized and Client-Server Architectures for DBMS • Two-Tier Client/Server Architectures for DBMSs Query Server or Transaction Server Data Storage on disk pages Local concurrency control and recovery Buffering and caching of disk pages Open Database Connectivity User interface and Data dictionary • Three-Tier and n-Tier Architectures for Web Applications

Classification of DBMS’s • Criteria to classify DBMS Systems Data Model Hierarchical and Network Model Relational Data Model Object Relational Data Model Native XML DBMS # of Users Single User System Multiple User System Database Distribution Centralized Distributed Homogeneous Heterogeneous Cost Open Source Licensed Limited Users Concurrent Users

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