RDBMS=== LECTURE CLASS I

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1. What is DBMS? Explain its features.

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A. In a typical file processing system, permanent records are stored in various files. A

number of different application programs are written to extract records from and add recordsto the appropriate files. But this method has a number of disadvantages, such as DataRedundancy, Difficulty in access, Data Isolation, Concurrent Access, Security Problems, andIntegrity Problems..

A Database Management System (DBMS) consists of a collection of interrelated data and a set of programs to access this data. This collection of Data is called Database. The Primary goal of a DBMS is to provide a convenient environment to retrieve and store database information.

Features of DBMS:-

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1.

The integration and sharing of data files minimizes the duplication and redundancy of

data to a great extent.

2.

Integration of data files also results in a considerable saving of storage space and in

data entry and data storage costs.

3.

Fewer application programs need to be developed for obtaining various reports due to independence of programs and data.

4.

The query language facility helps non-programming persons to access the database

for information as needed without the help of any programmer.

5.

Faster preparation of information to support non-recurring tasks and changing

conditions is possible.

6.

Updation of data becomes easier due to integration of data file. Fewer errors may

when several records may be updated simultaneously.

7.

Large database maintenance.

Software Engineering

Software Engineering is concerned with

•  Technical processes of software development
•  Software project management
•  Development of tools, methods and theories to support software production
•  Getting results of the required quality within the schedule and budget
•  Often involves making compromises
•  Often adopt a systematic and organized approach
•  Less formal development is particularly appropriate for the development of web-based systems

Software Engineering is important because

•  Individuals and society rely on advanced software systems
•  Produce reliable and trustworthy systems economically and quickly
•  Cheaper in the long run to use software engineering methods and techniques for softwaresystems

Fundamental activities being common to all software processes:

•  Software specification: customers and engineers define software that is to be produced and the constraints on its operation
•  Software development: software is designed and programmed
•  Software validation: software is checked to ensure that it is what the customer requires
•  Software evolution: software is modified to reflect changing customer and market requirements

Software Engineering is related to computer science and systems engineering:

 Computer science

o Concerned with theories and methods

 Software Engineering

o Practical problems of producing software

 Systems engineering

o Aspects of development and evolution of complex systems

o Specifying the system, defining its overall architecture, integrating the different parts to 

create the finished system

General issues that affect many different types of software:

 Heterogeneity

o Operate as distributed systems across networks

o Running on general-purpose computers and mobile phones

o Integrate new software with older legacy systems written in different programming 

languages

o Challenge: build dependable software that is flexible enough to cope with heterogeneity

 Business and social change

o Change existing software and rapidly develop new software

o Traditional software engineering techniques are time consuming

o Goal: reduce time to adapt to changing needs

 Security and trust

o Software is intertwined with all aspects of our lives

o See remote software systems (web page, web service interface)

o Make sure malicious users cannot attack software and information security is 

maintained

Essential attributes of good software

 Maintainability

 Dependability and security

 Efficiency

 Acceptability

Application types

 Stand-alone applications

 Interactive transaction-based applications

 Embedded control systems

 Batch processing systems

 Entertainment systems

 Systems for modeling and simulation

 Data collection systems

Types of Programming Language

Low Level Language

• First-generation language is the lowest level computer language. Information is conveyed to the computer by the programmeras binary instructions
• Binary instructions are the equivalent of the on/off signals used by computers to carry out operations. The language consists of zeros and ones.

Advantages

Ø  Fast and efficient

Ø  Machine oriented

Ø  No translation required

     Disadvantages

Ø  Not portable

Ø  Not programmer friendly

Assembly Language

Assembly or assembler language was the second generation of computer language. By the late 1950s, this language had become popular. Assembly language consists of letters of the alphabet. This makes programming much easier than trying to program a series of zeros and ones. As an added programming assist, assembly language makes use of mnemonics, or memory aids, which are easier for the human programmer to recall than are numerical codes.

Assembler

An assembler is a program that takes basic computer instructions and converts them into a pattern of bits that the computer's processor can use to perform its basic operations. Some people call these instructions assembler language and others use the term assembly language In other words An assembler is a computer program for translating assembly language — essentially, a mnemonic representation of machine language — into object code. A cross assembler (see cross compiler) produces code for one processor, but runs on another.

As well as translating assembly instruction mnemonics into opcodes, assemblers provide the ability to use symbolic names for memory locations (saving tedious calculations and manually updating addresses when a program is slightly modified), and macro facilities for performing textual substitution — typically used to encode common short sequences of instructions to run inline instead of in a subroutine.

High Level Language

The introduction of the compiler in 1952 spurred the development of third-generation computer languages. These languages enable a programmer to create program files using commands that are similar to spoken English. Third-level computer languages have become the major means of communication between the digital computer and its user. By 1957, the International Business Machine Corporation (IBM) had created a language called FORTRAN (FORmula TRANslater). This language was designed for scientific work involving complicated mathematical formulas. It became the first high-level programming language (or "source code") to be used by many computer users.

Within the next few years, refinements gave rise to ALGOL (ALGOrithmic Language) and COBOL (COmmon Business Oriented Language). COBOL is noteworthy because it improved the record keeping and data management ability of businesses, which stimulated business expansion.

Advantages

Ø  Portable or machine independent

Ø  Programmer-friendly

Disadvantages

Ø  Not as efficient as low-level languages

Ø  Need to be translated

Examples : C, C++, Java, FORTRAN, Visual Basic, and Delphi.