Database Design & Management

Contents (Summary) Concepts of Database Management Database Designing and Modelling Client-Server Architecture, Data Dictionaries SQL DDL,DML,Views ,Constraints Oracle SQL Distributed Database Object oriented database Database Administration

Method of Delivery Text Books Reference Book/s Lecture Slides Lab work (SQL) Helping notes or Reference website (email)

Key to success Punctuality Hard work Practice Devotion Dedication

Text Book (1) Modern Database Management By: Fred McFadden, Jeffrey Hoffer, Mary Prescott 5th Edition, Addison Wesley (2) Database Systems Concepts By: Silberschatz., Korth., Sudarshan 4th Edition (3) Database Systems By: Thomas Connolly, Carolyn Begg 3rd Edition (4) An Introduction to Database Systems By: C.J.Date

What is Data ?

Definition of Data Data consists of Facts, text, graphics, images, sound and video segments that have meaning to user’s environment. Data can exist in a variety of forms: - As numbers or text on pieces of paper - As bits and bytes stored in electronic memory - As facts stored in a person's mind.

Data Type Data is what we measure Data type refers to the classification of a particular type of information integer floating point character, string date student record blob (binary large object)

Data in Context Large volume of facts, difficult to interpret or make decisions based on

INFORMATION Data that has been processed in such a way that it can increase the knowledge of person who uses it

Useful information that managers can use for decision making and interpretation

Data vs Information Data into information Summarise data Data In context (table) Decision support We use Database term without distinguish data or information

ACTIVITY Please write down the data for cricket match bowling Do you get any information??

Definition of Database “ Database is a shared collection of logically related data, designed to meet the information needs of multiple users in an organization ” Database is designed, built, and populated with data for a specific purpose. It has an intended group of users and preconceived applications in which these users are interested.

Alternative Terminology Formal terms are mostly used for technical users. Data processing terms are more natural for non technical users.

Computerized File Based Processing System

Computerized File-based Processing File handling routines & File definition Sales files Sales File handling routines & File definition Contracts files Contracts

File-based Systems A collection of application programs that perform services for the end users (e.g. reports). Each program defines and manages its own data.

Three file processing systems Duplicate Data

Limitation of Computerized File-based Approach Separation and Isolation of data Each application maintains its own set of data. Users of one application may be unaware of potentially useful data held by other applications. Duplication of data (data redundancy) Same data is held by different files. Limited Data Sharing No centralized control of data Lengthy Development Times Programmers must design their own file formats Excessive Program Maintenance 80% of information systems budget

Limitation of File-based Approach Accessibility Data is stored using programs that are written in different languages and format Cannot easily access other files due to incompatible file format. No control over access and manipulation of data beyond that imposed by application programs. Hard Coded Queries (Data dependence) File structure and all definition of data are defined in the application program code. Programs are written to satisfy particular functions / requirements. Any new requirement needs a new program.

Problems with Data Dependency Each application programmer must maintain their own data Each application program needs to include code for the metadata of each file Each application program must have its own processing routines for reading, inserting, updating and deleting data Lack of coordination and central control Non-standard file formats

Problems with Data Redundancy Waste of space to have duplicate data Causes more maintenance headaches The biggest Problem: When data changes in one file, could cause inconsistencies Compromises data integrity

Database Processing System SOLUTION: Database Processing System

Database Processing Sales Database Contracts Sales Application DBMS

The DATABASE Approach Central repository of shared data Data is managed by a controlling agent Stored in a standardized, convenient form Requires a Database Management System (DBMS)

Database Management System DBMS Database containing centralized shared data Application #1 #2 #3 DBMS manages data resources like an operating system manages hardware resources

Database Management System (DBMS) A collection of programs that enables users to define,create and maintain and control access to the database. General-purpose software system that facilitates the processes of defining, constructing and manipulating databases for various applications. Defining - specifying data types, structures, constraints. Constructing - storing of data Manipulation - querying, updating and reporting.

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

Database Management System A DBMS is a data storage and retrieval system which permits data to be stored non-redundantly while making it appear to the user as if the data is well-integrated.

Advantages of Database Approach Program-Data Independence Metadata stored in DBMS, so applications don’t need to worry about data formats Data queries/updates managed by DBMS so programs don’t need to process data access routines Results in: increased application development and maintenance productivity Minimal Data Redundancy Leads to increased data integrity/consistency

Advantages of Database Approach Improved Data Sharing Different users get different views of the data Enforcement of Standards All data access is done in the same way Improved Data Quality Constraints, data validation rules Better Data Accessibility/ Responsiveness Use of standard data query language (SQL) Security, Backup/Recovery, Concurrency Disaster recovery is easier

Costs and Risks of the Database Approach Up-front costs: Installation Management Cost and Complexity Conversion Costs Cost of DBMS Additional hardware costs. Ongoing Costs: Requires New, Specialized Personnel Need for Explicit Backup and Recovery Higher impact of a failure Organizational Conflict: Old habits die hard

The Range of Database Applications Personal Database – standalone desktop database Workgroup Database – local area network (<25 users) Department Database – local area network (25-100 users) Enterprise Database – wide-area network (hundreds or thousands of users)

Personal Computer Database

Workgroup database with local area network

An enterprise data warehouse

Components of DBMS Environment 1. Hardware Can range from a PC to a network of computers. 2. Software DBMS itself and operating system, including any network software if network is being used. 3. Data Includes actual data used by the organization, and description of data (schema). Also a system catalog contains data such as the names of authorized users.

Components of DBMS Environment 4. Procedures Instructions and rules that should be applied to the design and use of the database, and the use of the DBMS. 5. People Data & Database Administrator Database Designer :- Logical & Physical Application Programmers End Users

DBMS Environment Bridge Data Software Procedures Hardware People Machine Human

Database System Environment Users/Programs Application Programs/Queries Software to Process Queries/Programs Software to Access Stored Data Stored Database Definition Stored Database

Evolution of DB Systems Flat files - 1960s - 1980s Hierarchical – 1970s - 1990s Network – 1970s - 1990s Relational – 1980s - present Object-oriented – 1990s - present Object-relational – 1990s - present Data warehousing – 1980s - present Web-enabled – 1990s - present

Summary Course Contents Data Information Data Vs Information Database Terms DBMS Advantages Disadvantages of DBMS Comparison of Computerized File Based Processing System & Database System