DBMS END SEM 2009

 SECTION A

1.      CASE -   Computer Aided Software Engineering

3.  Encryption is the conversion of data into a form, called a ciphertext, that cannot be easily understood by unauthorized people.

Decryption – process of converting encrypted data back into its original form, so it can be understood. (Reverse process of encryption)

 

6. Specialization

·        Top-down design process;

·        We designate sub groupings within an entity set that are distinctive from other entities in the set.

·        These sub groupings become lower-level entity sets that have attributes or participate in relationships that do not apply to the higher-level entity set.

Extra Note :

Generalization – Reverse process of specilisation.

7. Data Warehouse - Integrated decision support system derived from various operational databases

10.

a)  Application Developer - A person who writes computer programs to meet specific requirements. The term often implies involvement with, or responsibility for, requirements capture and testing , in contrast to the term programmer .

               An individual who develops a business application and usually performs the duties of a systems analyst and application programmer.

b) End Users – people who use the applications and databases

 

c) A database administrator (DBA) is a person responsible for the design, implementation, maintenance and repair of an organization's database.

 

The role includes the development and design of database strategies, monitoring and improving database performance and capacity, and planning for future expansion requirements. They may also plan, co-ordinate and implement security measures to safeguard the database

 

11. The arithmetic unit, also called the arithmetic logic unit (ALU), is a component of the central processing unit (CPU). It is often referred to as the “engine” of the CPU because it allows the computer to perform mathematical calculations, such as addition, subtraction, and multiplication. The ALU also performs logic operations, like “AND,” “OR,” and “NOT.”

 

13. The costs and risks are of DB approach are

·         New specialized Personal     

• Installation and management cost and complexity
• Conversion costs
• Need for explicit backup and recovery
• Organizational conflict

16.   Advantages of Database System

·        Reduced data redundancy

·        Reduced updating errors and increased consistency

·        Greater data integrity and independence from applications programs

·        Improved data access to users through use of host and query languages

·        Improved data security

·        Reduced data entry, storage, and retrieval costs

·        Facilitated development of new applications program

 

19. SDLC is Software Development Life Cycle. It is used to develop the software systematically . 

SDLC have main 7 Stage: 

1. Preliminary Investigation 

2. Feasibility Study

3. Analysis

4. Design 

5. Coding 

6. Testing 

7. Maintenance & Review.

 SDLC is the process of developing information systems through  investigation, analysis, design, implementation and  maintenance. SDLC is also known as information systems development or application development. SDLC is a systems approach to problem solving and is made up of several  phases, each comprised of multiple steps:

The software concept - identifies and defines a need for the new system 

A requirements analysis - analyzes the information needs of the end users 

The architectural design - creates a blueprint for the design with the necessary specifications for the hardware, software, people and data resources 

Coding and debugging - creates and programs the final system 

System testing - evaluates the system's actual functionality in relation to expected or intended functionality.

 

21.

 

a)        

           A database consists of an organized collection of data for one or more uses, typically in digital form.

One way of classifying databases involves the type of their content

 

Eg:   bibliographic, document-text, statistical.

 

b) DBMS, is a computer software program that is designed as the means of managing all databases that are currently installed on a system hard drive or network. Different types of database management systems exist, with some of them designed for the oversight and proper control of databases that are configured for specific purposes. Here are some examples of the various incarnations of DBMS technology that are currently in use, and some of the basic elements that are part of DBMS software applications.

 

 

The advantages of DBMS are as follows: 
-Controlling redundancy 
-Providing storage structure for efficient query processing. 
-Restricting unauthorized users. 
-Providing concurrency. 
-Providing backup and recovery. 
-Enforcing integrity constraints. 

 

25. DDL

Data Definition Language (DDL) statements are used to define the database structure or schema. Some examples:

• CREATE - to create objects in the database
• ALTER - alters the structure of the database
• DROP - delete objects from the database
• TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
• COMMENT - add comments to the data dictionary
• RENAME - rename an object

DML  

Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples:

• SELECT - retrieve data from the a database
• INSERT - insert data into a table
• UPDATE - updates existing data within a table
• DELETE - deletes all records from a table, the space for the records remain
• MERGE - UPSERT operation (insert or update)
• CALL - call a PL/SQL or Java subprogram
• EXPLAIN PLAN - explain access path to data
• LOCK TABLE - control concurrency