DBMS TWO MARK Q&A

1.what is  DBMS ?

DBMS stands for Database Management System. A DBMS receives request from applications and translates those  request into action on a specific database. A DBMS processes SQL statement or uses other functionality to create, process and  administer databases.

2.What is Normalization?

It is a process  of analyzing  the given relation schemes  based on their functional dependencies(FDs) and  primary key to achieve  the :

1)minimizing redundancy

2)minimizing insertion

3)Deletion and update anomalies

3.What  is Database?

A   Database  is a logically  coherent  collection  of data with some  inherent  meaning, representing  some aspect of real  world and which is designed, built and populated with data for a specific purpose.

4.what is Data base system?

The  database and  DBMS  software together is called as Database system.

5.What are the advantages  of DBMS?

1.Redunancy is controlled

2.unauthorized  access is restricted

3.providing multiple  user interfaces

4.enforcing  integrity constraints

5.providing backup and recovery.

6.Define Entity?

It is a’thing’ in the real  world with an independent existence.

7.What are the basic components of  a DBMS?

->user

->Database application

->DBMS

->database.

8.What  are Data?

Data is  a collection of information  stored in a database as one of several different databases.

9.What is  data dictionary?

Data dictionary  is a repository  of information describing the data in the database that is  meta data. data dictionary is a file that contains meta data or data about data

10.What are the various types of database?

The different types of  database:

Multimedia database

Spatial database

Real time or archieve database

Data warehouse or on-line analytical

Processing database

11.Define class diagram?

DBMS  focuses on data only because its  always table.The  basic data is always useful and remains unchanged.Only the procedures and the report  generation are constantly changed.The  database focuses on defining  the table correctly.

12.What is 1^st NF?

1^st  is a relation in which the intersection of each row and column contains one and only one value.To  transform the unnormalized table(a table contains one or more repeating groups) to 1stNF,we identify and remove the repeating groups within the table.

UNIT 2

1.Define  SQL?

Structured query language is the  standard  command set   used to communicate with the relational database management system.

2.What are the advantages of SQL?

SQL is a high level language  that  provides a greater degree of abstraction than procedural language.

The language while being simple and easy to learn can handle complex situations

Application written is SQL  can be easily ported across system.

3.What are the six main  categories of SQL commands?

1.Data Definition Language(DDL)

2.Data Manipulation Language(DML)

3.Data Query Language(DQL)

4.Data  Control Language(DCL)

5.Transactional Control Commands(TCC)

*view definition  language(vml)

*storage  definition  language(sdl)

4.Define DDL?

DDL stands for Data definition language. data definition language is used to  create, alter, drop, replace and truncate database objects.

5.Define DML?

DML stands for data  manipulate language

 data manipulate language commands   let users insert, modify and delete the data in the database.

SQL  provides three  data  manipulation statements insert, update and delete.

6.Define  DCL?

DCL  stands for data control language. It consist of commands that control the  user access to the  database object.

7.What are transactional   control commands?

*commit

*rollback

*save point

           *set transactions

8.What is a set function?

A set function is a type of function that processes or calculates.  Data and returns the appropriate value.

9.what is  refrential   integrity?

A value that appears in one relation for a  given set of attributes, Also  appears for a certain  set of attributes in another relation.

10.What is trigger?

Trigger are a special type of stored procedure, which gets involved upon a certain event. They can be  performed upon an insert, update and delete.

11. What is the purpose of WHERE clause in an update statement?

The WHERE clause specifies a condition or a set of conditions that act as a filter for the rows that are updated. Only the rows that meet the specified conditions are updated.

12.Describe Aggregate functions?

This takes the collection of values and return a single value as a result. SQL provides seven built-in functions to facilitate query processing. The seven built-in functions are COUNT, MAX, MIN, SUM, AVG, STD EN and VARIANCE.

13. What is outer join?

A generic term that represents a left join or a right join. It returns rows from a table, even if there is no matching row in the other table.

14. Define Query by example (QBE)?

A fill-in-the form approach to designing queries. You select tables and columns from a list and fill in blanks for conditions and sorting. It is relatively easy to use, requires minimal typing skills, generally comes with a Help system, and is useful for beginners.

15. What is subqueries?

Subqueries are nested SELECT statements. In simple  words, they are ‘SELECT WITHIN A SELECT’. Subqueries enable the user to base the search criteria of a SELECT statement  the result of another SELECT statement. A sub query is the most natural way of expressing a query.

16.SQL datatypes

*character(n)

*character varying(n)

*decimal(p,q)

*integer

*smallint

*float

17.Define TCL?

TCL are statements, which manage  all the changes made by the DML   statement. For ex, transaction  control  statement are COMMIT,ROLLBACK,SAVE POINT and TRANSCATION.

18.Write about CREATE statement with  syntax?

By using the CREATE statement we can create the new table. The general syntax:

  CREATE TABLE <table name> ( <COLUMN1> <TYPE1>,<COLUMN2> <TYPE2>,…………);

19.Explain ALTER  command?

An existing base table can be modified by using the ALTER TABLE statement. The syntax is:

ALTER TABLE table name ADD/MODIFY column data-type [NULL[NOT NULL WITH  DEFAULT];

20.How to delete the table?

An existing table can be deleted at any time by using the DROP command. The syntax is :

DROP TABLE table name

21.What is SELECT statement?

To get data from the tables in a database, we use the SELECT  use to retrieve any data.

SELECT[ALL/DISTINCT] scalar expression(s)

FROM table(s)[WHERE conditional expression]

[GROUP BY column(s)][HAVING conditional expression]

[ORDER BY column(s)];

22.Differentiate between  Subqueries&  SELECT?

->A sub query must produce a single column of data as in result. In other words, the sub query can have onlya single select item in its SELECT clause.

->A sub query  cannot be a UNION, only a single SELECT statement is allowed.

UNIT-3

1.What is sub form?

A form that is displayed inside another form .The data in the sub form is generally linked to the row currently being displayed on the  main form.

2.Define form?

Forms are used to collect data, display results of queries, display analysis, and perform computations. They are used as

·         Collect data

·         Display query results

·         Display analysis and computation

·         Switchboard for other forms and reports

·         Direct manipulation of objects

·         Graphics

·         drag and drop

They are also used as switch boards, or connectors, to other forms.

3. Define report?

Reports are typically printed on paper, but they are increasingly being created for direct display on the screen. reports are used to format the data  and present results from complex analysis. reports can be detailed and cover several pages.

4.What  are the factors  responsible for designing the form?

·         user control
·         consistency
·         clarity
·         aesthetics
·         feedback
·         forgiveness

5.what are the types of forms?

1. Tabular forms-which displays data in rows and columns,

2. Single-row forms, which show data for one row at a time and in which the designer can arrange the values in any format on the screen,

3. Subforms, which display data from two tables that have one-to-one-many relationship,

4. Switchboard forms, which direct the user to other forms and reports in the application

6.what are the properties of forms?

·         Data-Base table/query, filter, sort

·         Integrity-edits, additions, deletions, locks

·         Format-caption, scroll bars, record selectors, navigation buttons, size and centering, background/pictures, colors, tab order

·         Other-pop-up menus, menu bar, help

7.what are types of reports?

There are three types of reports

·         Tabular

·         Groups  or subtotals

·         Labels

8.what is  PL?

Procedural language is the  generic term for a traditional programming language such as BASIC,COBOL,C++,or java that evaluates commands  in  order and contains certain basic logic elements.

9.How to code DBMS?

Three comman methods are used to code

*within the forms and reports

*within the queries as an extension to sql

*embedded within the an external program

10.Difference between forms and reports?

·         Reports are designed to be printed.

·         Forms are displayed on the screen.

·         Reports are generally used to present summarized data.

·         Forms can be used to collect data.

·         Report can combine both detailed and summarized data.

·         Forms can easily handle multiple pages of output.

UNIT-4

1.Define application?

Applications are complete system that perform specific tasks. The task is defined by the user. The goals of application is to provide information and help user make decisions.

2. What is the power of  application?

Applications serve two primary functions:

1. They establish and control the user interface

2. They ensure data integrity.

3. What is the features of data integrity?

·         Data validation

·         Automatic computation

·         Verification of totals

·         Control of user access

·         Transaction integrity

·         Backup and recovery

4. Define data trigger?

Data trigger are procedures that are executed when a command attempts to alter the database itself .It enable you to provide detailed control over the database.

5. What is transaction?

A transaction is defined as a set of changes that must all be made together .It involve multiple changes to the database, all of the changes.

6. What is the relation between application and the user?

The overall structure is an important feature of any application. The structure or layout defines how the user deal with the application. Most database applications will use forms and reports as individual components.

7. What is switchboard forms?

The main menu or switchboard forms is an element many developers like to use. The main purpose   of the switchboard form

·         Directory for the application

·         Identify users

·         Startup  and shutdown code

·         Can preload forms in background

·         Make  them invisible

8. What is user interface feature?

Modern windows-based application have several user interface features that are designed to standardize the look and feel of application and to make your application relatively easy to use. Three features are particularly important: menus, tool-bars and the Help system.

9. Define Custom report?

Reports writers are good at formatting data common reports. Some report writers are powerful enough to handle complex reports. Yet you might encounter reports that are difficult to create with a report writer.

10. What is control break?

Grouping data and producing subtotals is known as a control break.

11. What is the important step in application?

The most important step is to make sure that the entire application will run from your forms-without the need to modify tables or entries using the access tools. You can build a simple Autoexec macro that opens your main switchboard form.

12. What are factors that affect the table?

     Three main categories that affect the table:

·         Retrieving data

·         Storing data

·         Reorganizing the database

13. Write down the methods to store the data?

·         Sequential storage

·         Pointers

·         Indexes

·         Binary search

·         Linked list

·         B⁺ tree

·         Hashed access

14. Define Data clustering?

If the two data items are required at the same time, by storing them close to each other, the computer can retrieve them in one pass. Clustering the data improves application speed by reducing the number of disk accesses.

15. What is data partitioning?

In some application some data items are accessed frequently and some are not. In this situation, separate the data item according to usage is called data partitioning.

16. What is the type of partitioning?

Horizontal partitioning and vertical partitioning.

17. What is RAID?

RAID stands for redundant array of independent drives.

The table is automatically split and stored on separate drives(striping).compared to systems that use a single drive, the system can store and retrieve data faster. Data also can be duplicated automatically for backup.

UNIT-5

1. What is data administration?

Data administration consist of the planning and coordination required to define data consistently throughout the company. It consist of technical aspects of creating and running the database.

2. write down the roles of Data Administrator(DA)?

·       Provide centralized control over the data

·         Data definition

·         Data integration

·         DBMS selection

·         Coordinate data integrity, security, and control

3. What is the usage of backup?

Back up takes a snapshot at one point in time. New changes are stored in the journal or log. Back up helps us to prevent from the external disaster.

4. What are the types of security?

There are two types of security:

Physical security& logical security

Physical security concern with the physically protecting the computing resources and preparing for physical disaster that might damage equipment or data.

 Logical security consist of protecting the data and controlling access to the data.

5. What is Hot site & Cold site?

A Hot site consist of a computer facility that has the system that help us to prevent from the physical disaster.

Whereas cold site or shell site is similar to the hot site but it does not have the communication and telecommunication equipment.

6. What SQL Command that is used in security process?

With the most database system the basic security permission can be set with the two SQL command:

            GRANT and REVOKE

The sql commands are useful for batch operations when you need to assign permission to a large number of tables or for several users at the same time. The visual tools are easier to use for single operations.

7. What is purpose of Oracle Security Manager?

Oracle Security Manager is the security manager is a visual tool to help assign access rights.it makes it easy to see what permission have already been assigned, but it does not show the owner permission.

8. What is encryption?

Encryption is a method of modifying the original information the original information according to some code so that it can be read only if the user knows the decryption key. Encryption can be used to transmit information from one computer to another.

9. Define Distributed Database?

A Distributed Database system consist of multiple independent database that operate on two or more computer that are connected and share data over a network.