Learning Outcomes Understand the basics and concepts of database systems.

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Learning Outcomes

Understand the basics and concepts of database systems.

Design, implement and evaluate a computer-based system, process, component, or program to meet desired needs

An ability to use current techniques, skills and tools necessary for computing practice

Chapter Outline

 Basic Definitions

Types of Database

Importance of Database Design

Role and Advantages of DBMS

DBMS Functions

 Historical roots

of Database

Example

 Databases are important for computing

Many computing applications deal with large amounts of information.

Database systems give a set of tools for storing, searching & managing this information.

Databases are a ‘core topic’ in both CS & IT.

 Basic concepts & skills with database systems are part of the skill set, student will be assumed to have as a CS or IT graduate.

 Concepts will be of use in other modules.

 Databases solve many of the problems encountered in data management

Used in almost all modern settings involving data management:

 Business

 Research

 Administration

 Important to understand how databases work and interact with other applications

Database:

1) A collection of related data.

2) A shared, integrated computer structure that stores a collection of

• End user data, that is, raw facts of interest to the end user.

• Metadata, or data about data, through which the end-user data are integrated and managed.

Data:

Known facts that can be recorded and have an implicit meaning.

Database Management System (DBMS):

A software package/ system to facilitate the creation and maintenance of a computerized database.

Database System:

The DBMS software together with the data itself.

Sometimes, the applications are also included.

 Data are raw facts

 Information is the result of processing raw data to reveal meaning

 Raw data must be formatted for storage, processing, and presentation

 Data: building blocks of information

 Information produced by processing data

 Accurate, relevant, timely information is the key to good decision making

 Data management: focuses on proper generation, storage, and retrieval of data

Databases can be classified according to the following

(i) Number of Users (ii) Database location

(iii) Extent of use

Number of Users:

Single-user : Supports only one user at a time. Also called

Desktop database

Multi-user : Supports multiple users at the same time.

If No. of users < 50 then it is called work-group DB

If No. of users >50 then it is called enter-prise DB.

Location:

Centralized DB : Supports data located at a single site.

Distributed DB: Supports data distributed across several different sites.

Extent of Use:

Operational / Transactional / Production: Designed primarily to support a company’s day-to-day operations.

Data Warehouse: Focuses primarily on storing data used to generate information required to make tactical or strategic decisions.

XML ( Extensible Markup Language):

A special language used to represent and manipulate data elements in textual format. Data can be stored in large text objects.

Database Design refers to the activities that focus on the design of the database structure that will be used to store and manage end-user data.

A well-designed database facilitates data management and generates accurate and valuable information.

Database System consists of logically related data stored in a single logical data repository

Database system eliminates file system’s data inconsistency, data anomaly, data dependency, and structural dependency problems.

The term Database System refers to an organization of components that define and regulate the collection, storage, management, and use of data within a database environment.

The database system is composed of five major parts. They are

1. Hardware 2. Software 3. People

4. Procedure 5. Data

1.Hardware: It refers to all the system’s physical devices; for example, computers, storage devices, printers, network devices.

2.Software: 3 types of software are needed: Operating system software, DBMS software, and application software.

Operating system software manages all hardware components and makes it possible for all other software to run on the computer. Example: Windows, Linux, Mac OS, Unix.

DBMS software manages the database within the database system.

Example: Microsoft SQL server, Oracle, MySQL, IBM DB2

Application programs and utility software are used to access and manipulate data in the DBMS and to manage the computer environment in which data access and manipulation take place.

These are most commonly used to access data found within the database to generate reports, tabulations, and other information to facilitate decision making.

Example: GUI’s provided with DBMS.

3. People/ Users:

 Users may be divided into

Those who actually use and control the database content, and those who design, develop and maintain database applications

(called “ Actors on the Scene ”), and

Those who design and develop the DBMS software and related tools, and the computer systems operators (called “ Workers

Behind the Scene ”).

 Actors on the scene

Database administrators:

 Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations.

Database Designers:

 Responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end-users and understand their needs.

End-users: They use the data for queries, reports and some of them update the database content. End-users can be categorized into:

Casual: access database occasionally when needed

 Naïve or Parametric: they make up a large section of the end-user population.

 Examples are bank-tellers or reservation clerks who do this activity for an entire shift of operations.

 Sophisticated:

 These include business analysts, scientists, engineers, others thoroughly familiar with the system capabilities.

 Stand-alone:

 Mostly maintain personal databases using ready-to-use packaged applications.

 An example is a tax program user that creates its own internal database.

4. Procedures:

These are the instructions and rules that govern the design and use of the database system. These are used to ensure that there is an organized way to monitor and audit both the data that enter the database and information that is generated through the use of that data.

5. Data:

Collection of facts stored in the database. It is raw material from which information is generated. Determination of what data is to be entered and how data are to be organized is a vital part of the database designer’s job.

DBMS is the intermediary between the user and the database

Database structure stored as file collection

Can only access files through the DBMS

DBMS enables data to be shared

DBMS integrates many users’ views of the data

 Advantages of a DBMS:

 Improved data sharing

 Improved data security

 Better data integration

 Minimized data inconsistency

 Improved data access

 Improved decision making

 Increased end-user productivity

 Data dictionary management

DBMS stores definitions of data elements and relationships (metadata) in a data dictionary

DBMS looks up required data component structures and relationships

Changes automatically recorded in the dictionary

DBMS provides data abstraction and removes structural and data dependency

Data storage management

DBMS creates and manages complex structures required for data storage

Also stores related data entry forms, screen definitions, report definitions, etc.

Performance tuning: activities that make the database perform more efficiently

DBMS stores the database in multiple physical data file

Data transformation and presentation

DBMS transforms data entered to conform to required data structures

◦ DBMS transforms physically retrieved data to conform to user’s logical expectations

Security management

DBMS creates a security system that enforces user security and data privacy

Security rules determine which users can access the database, which items can be accessed, etc.

Backup and recovery management

DBMS provides backup and data recovery to ensure data safety and integrity

Recovery management deals with recovery of database after a failure

 Critical to preserving database’s integrity

Multiuser access control

DBMS uses sophisticated algorithms to ensure concurrent access does not affect integrity

Data integrity management

DBMS promotes and enforces integrity rules

 Minimizes redundancy, Maximizes consistency

Data relationships stored in data dictionary used to enforce data integrity

Integrity is especially important in transaction-oriented database systems

Database access languages and application programming interfaces

DBMS provides access through a query language

Query language is a nonprocedural language

Structured Query Language (SQL) is the de facto query language

 Standard supported by majority of DBMS vendors

 Database communication interfaces

Current DBMSs accept end-user requests via multiple different network environments

Communications accomplished in several ways:

 End users generate answers to queries by filling in screen forms through Web browser

 DBMS automatically publishes predefined reports on a Web site

 DBMS connects to third-party systems to distribute info. via e-mail

 Early Database Applications:

The Hierarchical and Network Models were introduced in mid 1960s and dominated during the seventies.

A bulk of the worldwide database processing still occurs using these models, particularly, the hierarchical model.

 Relational Model based Systems:

Relational model was originally introduced in 1970, was heavily researched and experimented within IBM Research and several universities.

Relational DBMS Products emerged in the early 1980s.

 Object-oriented and emerging applications:

Object-Oriented Database Management Systems (OODBMSs) were introduced in late 1980s and early 1990s to cater to the need of complex data processing in CAD and other applications.

 Their use has not taken off much.

Many relational DBMSs have incorporated object database concepts, leading to a new category called object-relational DBMSs (ORDBMSs)

 Data on the Web and E-commerce Applications:

Web contains data in HTML (Hypertext markup language) with links among pages. This has given rise to a new set of applications and Ecommerce is using new standards like XML (eXtended Markup

Language).

Script programming languages such as PHP and JavaScript allow generation of dynamic Web pages that are partially generated from a database.

 Also allow database updates through Web pages.

 New functionality is being added to DBMSs in the following areas:

Scientific Applications

XML (eXtensible Markup Language)

Image Storage and Management

Audio and Video Data Management

Data Warehousing and Data Mining

 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.

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