HOMEWORK

OF

“DBMS”

Course Code: CAP301

SUBMITTED BY: submitted to:

RAJIV RAJAN LECT: RITU RAI

RD3804B2

M.C.A 3sem

1.QNS Discuss the problems that are caused by data redundancies? Can data redundancies be completely eliminated when the database approach is used? Why or why not? 

ANS: The same piece of information may be stored in two or  more files. For example – the particular of an individual who may be a  customer or an employee may be stored in two or more files. Some of these information may be changing., such as the address, the pay drawn, etc. it is therefore quite possible that while the address in the master file for one application has been updated the address in the master file for one  application has been updated the address in the master file for another application may have not been. It may not also be easy for the computer   based system to even find out as to in how many files the repeating items such as the address if occurring.

The solution there for is to avoid this data redundancy and the keeping of multiple copies of the same information and replace it by a system where the address is stored at just one place physically, and is accessible to all applications from this itself.  Reduction of Redundancies: centralized control of data by the DBA avoids unnecessary duplication of data and effectively reduce the total amount of data in a large mass of data. Another advantage of avoiding duplication is  the elimination of the inconsistencies that tend to be present in redundant data files. Any redundancies that exist in the DBMS are controlled and system ensures that these multiple copies are consistent.

2.QNS: why is data important to an enterprise? How does an enterprise that has better control of its data have competitive edge over other organizations? What are the various areas and benefits where the DBMS can be use? 

ANS: There are several reasons for spending money, time, and effort on data protection. The primary one is minimizing financial loss, followed by compliance with regulatory requirements, maintaining high levels of productivity, and meeting customer expectations. As computers have become more and more integral to business operations, data requirements from regulators such as the U.S. Securities and Exchange Commission (SEC), as well as from customers, have been imposed on businesses. There is a clear expectation that important data be available 24 hours a day, 7 days a week, 365 days a year. Without a working data protection strategy, that isn't possible.

The single most important reason to implement data protection strategies is fear of financial loss. Data is recognized as an important corporate asset that needs to be safeguarded. Loss of information can lead to direct financial losses, such as lost sales, fines, or monetary judgments. It can also cause indirect losses from the effects of a drop in investor confidence or customers fleeing to competitors. Worse yet, stolen or altered data can result in financial effects that are not known to the company until much later. At that point, less can be done about it, magnifying the negative resultsA third driver, which does not get the attention of the press but is important to organizations nonetheless, is productivity. Loss of important data lowers overall productivity, as employees have to deal with time-consuming customer issues without the aid of computer databases. Data loss also results in application failures and similar system problems, making it

difficult for people to do their jobs. A poor data protection strategy may leave people waiting for long periods of time for systems to be restored after a failure. During that time, employees may be idle or able to work only in a reduced capacity, further diminishing productivity.

Database Management system:It is abbreviated as DBMS. It is a software through which we can create , edit and retrieve our database. Database is actually a collection of related data. Database Management is basically a software used to monitor the database of any organization where they are implemented . Organizations uses different types of software's. DBMs has many advantages, listed below

• Data is integrated: means all related data on different computers are linked in such away that all data are linked with each other.• Data duplication is reduced : As data is integrated ,present on different locations so chances of data duplication are much reduced and date is updated form.

• Data is easy to understand: As data is managed according to the needs of the user and it is in very easy format so that you have no difficulty in using the data through database management system• Data Validity : Using DBMS your data is more valid and there are less chances that data is orthodox. And there are different checks are applied to check either valid data is entered or not.• Data Security : using DBMS your data is much secured. Only the relevant users know the required software to operate.

3.QNS: four responsibilities of a database management system. For each responsibility, explain the problem that would arise if the responsibility were not discharged? 

RESPONSIBILITIES

Designing & creating relational database objects such as tables, views & indexes; Supporting and maintaining the environment a relational database requires to properly function (i.e., security, recovery, backup & reorganizations) ; Ensuring that relational database access code performs efficiently (i.e., SQL review, database monitoring).

Developing & maintaining naming standards for database objects such as tablespaces, tables, indexes & views Participating in database migration reviews Assisting in product installation & reviewing initial installation options; for Oracle, the Central DBA will assist in product installation and specify initial installation options roviding functional guidance to the systems programmer & the operator. For Oracle, the Central DBA will provide this functional guidance to the Unix System Administrator. Evaluating & testing DBMS related software Develop operational procedures Supporting, monitoring & tuning the database subsystems & instances; for Oracle this includes starting and stopping the instances, listeners, and intelligent agents Participate in selecting database management support tools Developing & implementing database administration policies & procedures including subsystem or instance security guidelines

4.QNS: consider the application program for the support of an automatic teller machine? How does such a program communicate with the user and the database?

ANS: Developers of many application programs (“applications”) implement the applications so that they can be customized by third parties. Typically, to customize an application received from a developer, a third party develops custom code (e.g., add-ins and document-level customizations) that uses functionality exposed by the application. The custom code may improve the usability of the applications or provide additional functionality (e.g., domain-specific functionality). Developers may provide “runtimes” that facilitate the development of custom code. A runtime is code that is loaded along with custom code and provides services to the custom code. These services may include higher-level functionality than that exposed by the application or may include domain-specific functionality. When an application is to load and start the execution of custom code, the application may load the runtime and direct the runtime to load and start the execution of the custom code.

execute to help ensure that an errant managed program will not unduly affect the execution of another managed program.

However, despite the many resources provided by the .NET Framework that act to develop and manage executable code, third parties that receive applications may be unfamiliar with certain functions of the environment, and may spend much time and effort in customizing applications. For example, they may be unfamiliar with the methodology or structure of the underlying code Additionally, the third party may be a customer of the application provider, and may wish to

In some embodiments, the system may customize applications to be used in ATM machines. For example, the applications may display information to users of ATMs, may receive input from the users, may transmit and receive messages to and from host systems, may detect events that have or have not occurred at the ATMs, and so on. The applications may interact with or support various “translets.” A translet is a component that provides one or more types of services to a user of an ATM. For example, a translet may provide account services, card or member services, financial supplies services, device management services, key or security services, and other services required or utilized during transactions or attempted transactions between a user and an ATM. The system, therefore, may enable a customer to modify the functionality of a translet or of selected translets, or may enable a customer to modify the functionality of an entire application.

In some embodiments, the system provides a wizard to a user that guides the user through the customization of applications. The user does not have to write any code, as some or all of the

code is generated by the wizard and implemented into the code of the application. The system enables a user to quickly and easily adapt, modify and/or customize a generic base application to meet the needs of the user, among other benefits.

5.QNS: Discuss the characteristics of relations that make them different from ordinary tables and files.

Ans:Tables and files have some particular order but relations don’t. ordinary tables and files are static while a relational database has data that is dependent on the data that is entered in tuples that are related to that attribute. in the ordinary tables and files, there are no constraints related to the related data and a user could input whatever they wanted.

6.QNS:Discuss the entity integrity and referential integrity constraints. Why is each considered important?

Ans:Integrity integrity constraints: The entity integrity constraints states that no primary key value can be NULL. This is because the primary key value is used to identify individual tuples in a relation. Having NULL values for the primary key implies that we cannot identify some tuples.

Entity Integrity Domain Integrity Referential integrity User-Defined Integrity

Entity Integrity ensures that there are no duplicate rows in a table.Domain Integrity enforces valid entries for a given column by restricting the type, the format, or the range of possible values.Referential integrity ensures that rows cannot be deleted, which are used by other records (for example, corresponding data values between tables will be vital).User-Defined Integrity enforces some specific business rules that do not fall into entity, domain, or referential integrity categories.Each of these categories of the data integrity can be enforced by the appropriate constraints. Microsoft SQL Server supports the following constraints:

PRIMARY KEY UNIQUE FOREIGN KEY CHECK NOT NULL

A PRIMARY KEY constraint is a unique identifier for a row within a database table. Every table should have a primary key constraint to uniquely identify each row and only one primary key constraint can be created for each table. The primary key constraints are used to enforce entity integrity.

A UNIQUE constraint enforces the uniqueness of the values in a set of columns, so no duplicate values are entered. The unique key constraints are used to enforce entity integrity as the primary key constraints.

A FOREIGN KEY constraint prevents any actions that would destroy link between tables with the corresponding data values. A foreign key in one table points to a primary key in another table. Foreign keys prevent actions that would leave rows with foreign key values when there are no primary keys with that value. The foreign key constraints are used to enforce referential integrity.

A CHECK constraint is used to limit the values that can be

placed in a column. The check constraints are used to enforce domain integrity.

A NOT NULL constraint enforces that the column will not accept null values. The not null constraints are used to enforce domain integrity, as the check constraints.