lesson 1 database

7/31/2019 Lesson 1 Database

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Lesson 1

Database- it is collection/storage of interrelated data, which allow user to retrieve,update and

manipulate very easily and as when its required. (similar in filing to cabinet).

DBMS- is data storage and retrieval system which permits data to store non redundantly whileWhile making it appear to user as if the data will integrated.

The Evolution of database Technology

1960s

Data collection, database creation, IMS (hierarchical database system by IBM) andnetwork DBMS.

1970s

Relational data model, relational DBMS implementation

1980s

RDBMS, advanced data models (extended-relational, OO, deductive, etc.) .

Application-oriented DBMS (spatial, scientific, engineering, etc.).

1990,s

Data mining, data warehousing, multimedia databases, and Webdatabases.

2000s

Stream data management and mining.

Data mining and its applications.

Web technology (XML, data integration) and global information systems.


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Database Approach

Self contained nature of database systems (database contains both

data and meta-data).

Data Independence: application programs and queries are

independent of how data is actually stored.

Data sharing.

Controlling redundancies and inconsistencies.

Secure access to database; Restricting unauthorized access.

Enforcing Integrity Constraints.

Backup and Recovery from system crashes. Support for multiple-users and concurrent access.

Advantages of Using the Database Approach

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

Disadvantage of database Approach Expensive

hardware, software, personnel, processing overhead, operating cost , etc. DBMS generality & overhead=> performance issue Increased vulnerability to failure

Recovery is more complex


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The Range of Database

1. Personal Database it is your personal data .

2. Workgroup Database- it is a workgroup basis.

example in your small business using the small network

3.Enterprise Database- system requires enterprises to evaluate their databae managementstrategies and enable them to manage relentless data growth and regulatory compliances which are a

crucial foundation for the unwired enterprise.

Example is the Database Ware housing.

Components of the Database Environment

Hardware

- Can range from a PC to a network of computers.

Software

- DBMS, operating system, network software (if necessary) and also the application

programs.

Data

- Used by the organization and a description of this data called the schema.

Procedures

- Instructions and rules that should be applied to the design and use of the database

and DBMS.

People

- The people that participate in the database environment.


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Database system development life cycle

Database planning is the management activities that allow the stages of the database system

development lifecycle to be realized as efficiently and effectively as possible.

System Definition involves identifying the scope and boundaries of the database system,including its major user views. A user view can represent a job role or business application area.

Requirements collection and analysis is the process of collecting and analyzing information

about the organization that is to be supported by the database system, and using this information

to identify the requirements for the new system.

Database design is the process ofcreating a design that will support the organizations missionstatement and mission objectives for the required database system. This stage includes the logical

and physical design of the database.

DBMS selection

The aim ofDBMS selection is to select a system that meets the current and future requirements

of the organization, balanced against costs that include the purchase of the DBMS product and

any additional software/hardware, and the costs associated with changeover and training.

Application design n involves designing the user interface and the application programs that

use and process the database. This stage involves two main activities: transaction design and userinterface design.

Transaction Design

An action, or series of actions, carried out by a single user or application program that accesses

or changes the content of the database.

There are three main types of transactions:

retrieval transactions

update transactions mixed transactions

User interface design

In addition to designing how the required functionality is to be achieved, we have to design an

appropriate user interface for the database system. This interface should present the required

information in a user-friendly way.


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Prototyping involves building a working model of the database system, which allows the

designers or users to visualize and evaluate the system.

There are two prototyping strategies in common use today:

Requirements prototyping and Evolutionary prototyping.

Requirements prototyping uses a prototype to determine the requirements of a proposed database

system and once the requirements are complete the prototype is discarded. While evolutionary

prototyping is used for the same purposes, the important difference is that the prototype is not

discarded but with further development becomes the working database system.

Implementation is the physical realization of the database and application designs.

Data conversion and loading involves transferring any existing data into the new database and

converting any existing applications to run on the new database.

Testing is the process of running the database system with the intent of finding programming

errors.

Operational maintenance is the process of monitoring and maintaining the system following

installation.

The process of monitoring and maintaining the database system following installation.

In this stage, the database system now moves into a maintenance stage, which involves the

following activities:

Monitoring the performance of the database system. If the performance falls below an

acceptable level, the database may need to be tuned or reorganized.

Maintaining and upgrading the database system (when required). New requirements are

incorporated into the database system through the preceding stages of the lifecycle.


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The Three Schema Architecture

The internal level:- The internal level has an internal schema which describes the physical

storage structure of the database.

The conceptual level:-The conceptual level has a conceptual schema, it describes the entities,

data types, relationships, user operations, and constraints.

The external level or view level:- The external or view level includes a number of external

schemas or user views. It describes the part of the database that a particular user group is

interested in and hides the rest of the database.


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Database Language

DDL For describing data and data structures a suitable description tool, a data definition language

(DDL), is needed. With this help a data scheme can be defined and also changed later.

Typical DDL operations (with their respective keywords in the structured query languageSQL):

Creation of tables and definition of attributes (CREATE TABLE ...)

Change of tables by adding or deleting attributes (ALTER TABLE )

Deletion of whole table including content (!) (DROP TABLE )

DML Additionally a language for the descriptions of the operations with data like store, search,

read, change, etc. the so-called data manipulation, is needed. Such operations can be done

with a data manipulation language (DML). Within such languages keywords like insert,

modify, update, delete, select, etc. are common.

Typical DML operations (with their respective keywords in the structured query languageSQL):

Add data (INSERT)

Change data (UPDATE)

Delete data (DELETE)

Query data (SELECT)

Database Interface

DBMS Interfaces

Types of interfaces provided by the DBMS include:

Interactive SQL can be used interactively from a terminal.

Menu-Based Interfaces for Web Clients or Browsing

Present users with list of options (menus) Lead user through formulation of request Query is composed of selection options from menu displayed by system.
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Forms-Based Interfaces

Displays a form to each user. User can fill out form to insert new data or fill out only certain entries. Designed and programmed for nave users as interfaces to canned transactions.

Graphical User Interfaces Displays a schema to the user in diagram form. The user can specify a query by

manipulating the diagram. GUIs use both forms and menus.

Natural Language Interfaces

Accept requests in written English, or other languages and attempt to understand them. Interface has its own schema, and a dictionary of important words. Uses the schema

and dictionary to interpret a natural language request.

Interfaces for Parametric Users

Parametric users have small set of operations they perform. Analysts and programmers design and implement a special interface for each class of

nave users. Often a small set of commands included to minimize the number of keystrokes required.

(I.e. function keys)

Interfaces for the DBA

Systems contain privileged commands only for DBA staff. Include commands for creating accounts, setting parameters, authorizing accounts,

changing the schema, reorganizing the storage structures etc.

lesson 1 database

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