Computer File 4th Sem

8/8/2019 Computer File 4th Sem

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Computer

Project Report

CONTENTS


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Introduction

Codds Rule

Structure Query Language

Types of SQL commands

Views Indexes

Type of Index

Using Index

SQL Commands

Bibliography


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INTRODUCTION

The foundation of Relational Database technology was laid by Dr. E.F. Codd, who in

his papers A Relational Model of Data for Large Shared Data Banks laid the basic

principle of the RDBMS. He laid down certain principle of database management,

referred to as relational model. The principles were soon applied to as experimental

systems, and start was made on the design of a database language that would

interact with such system.

The relational model was evolved through many stages since its inception in the

early 1970s. Performance of the model was an early concern. However, performance

can be measured in the two ways performance at execution time and performanceduring design and implementation. In the first case we measure the performance

when the database is under construction. In the second case the relational model

was a clear winner from the start outperforming both hierarchical and network

models by considerable margins. Although its critics attacked the slow processing

speeds of the earlier relational implementation, the relational model no longer

suffers from these shortcomings.

The access language SQL, together with its earlier predecessors and competitors,also received a lot of criticism. Early version of SQL was not uniform and

standardized in the treatment of certain concepts. But with the introduction of ANSI

SQL standards, this problem- the lack of standardization also got resolved.

CODDS RULE


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Dr. E.F.Codd was the founder of RDBMS and he laid down certain principle of

database management system referred to as RDBMS. He provides a set of

following 12 rules which qualify a database product as relational:-

1. Information Rule All information in a relational database including table

names, column names is represented by values in a table. This view speeds

up the design and learning process. User productivity is improved since

knowledge of only one language is necessary to access all data such as table

description, attribute definition, integrity constraints, etc.

2. Guaranteed Access Rule Every piece of data in a relational database

can be accessed by using a combination of a table name, a primary key value

that uniquely identifies a record.

3. Systematic Treatment of Null Values The RDBMS handles records

that have unknown or inapplicable values in a pre-defined manner. Also, the

RDBMS distinguishes between zeroes, blanks and nulls in the records and

handles such values in a consistent manner that produces correct answers,

comparisons and calculations

4. Active On-lone Catalog Based on Relational Model : - The description

of database and its contents are database tables and therefore can be queried

online via data manipulation language. The Database Administrator

productivity is improve since changes and additions to catalog can be done

with same commands that are used to access any other table.

5. Comprehensive Data Sub-language Rule :- The RDBMS may support

several languages. But at least one of them should allow the user to do all the


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following: define tables and views, query and update data, set integrity

constraints, set authorizations and define transactions. User productivity is

improved since there is just one approach that can be used for all database

operations.

6. View Updating Rule :- Any view that can be updated theoretically can be

updated using the RDBMS. Data consistency is ensured since the changes

made in the view are transmitted to base table and vice versa.

7. High Level Insert, Update and Delete :- The RDBMS supports insertion,

updating and deletion at a table level. The performance is improved since the

commands act on a set of records rather than one record at a time.

8. Physical Data Independence :- The execution of adhoc request and

application programs is not affected by changes in the physical data access

and storage methods. Database administrator can make changes to the

physical naccess and storage method which improve performance and do not

require changes in the application programs or requests.

9. Logical Data Independence :- Logical changes in tables and views such

as adding/deleting columns or changing field lengths need not necessitate

modifications in programs or in the format of ad hoc requests. The database

can change and grow to reflect changes in reality without requiring user

intervention or changes in the applications .

10. Integrity Independence :- Like table and view definitions, integrity

constraints are stored in the on-line catalog and can therefore be changed


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without necessitating changes in the application programs. Integrity

constraints specific to a particular Relational Database must be definable in

relational data sub-language and storable in catalog.

11. Distribution Independence :- Application programs and ad hoc

requests are not affected by changes in distribution of physical data. This

improves system reliability since application programs will work even if the

programs and data are moved to different sites.

12. Non subversion Rule :- If the RDBMS has a language that access the

information of a record at a time, this language should not be used to bypass

the integrity constraints. This is necessary for data integrity.

STRUCTURE QUERY LANGUAGE


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Structured Query Language (SQL) is the standard command set used to

communicate with the relational database management systems. All the tasks

related to relational data management creating tables, querying the database for

information, modifying the data in the database, deleting them, granting access to

users, and so on can be done using SQL. Different database vendors use differentdialects of SQL.

The basic features of all these different flavors are the same they have the same

base, the ANSI SQL standard. Implementation of the advanced features of SQL

differs from vendor to vendor, but here also the concepts are the same. So the SQL

skills are very much transferable. In other words, except for the vendor specific

enhancements, the SQL is the same.

An outstanding functionality of SQL is its support for automatic navigation to the

target data. This functionality enables the user to specify what information is

required and not how to get it. The SQL user does not need to know how data is

stored. The query language takes care of retrieving, replacing, adding and deleting

data thus making the database readily accessible to end users who have little or no

knowledge of programming.

Relational query processing for non-procedural language assumes simplification. Itis useful for task like data analysis, reporting and planning.


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A procedural programming language needs every specification about data. These

includes storage, access mode and retrieval of data, file control operations like

open and close, and linking files and functions. SQL is simpler in operation than

procedural languages like C/C++ for database management. Procedural language

like C/C++ are more suited for system programs that interact with the hardware or

communicate between computers.

The greatest advantage of using SQL is that while developing applications,

programmers are more productive as they can concentrate on the essential logic

and data requirements of their applications. They do not have to spend time on the

detail of data representation.

Although SQL is the default language used in an RDBMS, MS-SQL Server has added

more features to the base level syntax of SQL and has its own SQL called Transact-

SQL (T-SQL).


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TYPES OF SQL COMMANDS

SQL can be classified based on its functionality. SQL provides a comprehensive set

of commands for a variety of tasks including the following:

Querying Data

Updating, inserting and deleting data

Creating, modifying and deleting database objects

Controlling access to the database

Providing for data integrity and consistency

SQL statements are divided into the following categories:

Data Definition Language (DDL)

Data Manipulation Language (DML)

Data Query Language (DQL)

Data Control Language (DCL)

Data Administration Statements (DAS)

Transaction Control Statements (TCS)


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FEATURES OF SQL

SQL is very powerful language that benefits all types of users of the RDBMS. You

use SQL to perform all tasks with the RDBMS. SQL is a very flexible language that

enables you to accomplish your development efforts. SQL enables you to work with

large groups of data rather than restricting you to single rows of data. Additionally,SQL permits the results of one query to be the input to another query statement.

1. Data Definition Language (DDL)

Data Definition Language is used to create, alter and delete database objects.

The commands used are CREATE, ALTER and DROP. The principal logical

data definition statements are CREATE TABLE, CREATE VIEW, CREATE

INDEX, ALTER TABLE, DROP TABLE, DROP VIEW and DROP INDEX.

2. Data Manipulation Language(DML)

Data Manipulation Language commands let users insert, modify and delete

the data in the database. SQL provides three data manipulation statement

INSERT, UPDATE and DELETE.

3. Data Query Language(DQL)

This is one of the most commonly used SQL statements. This SQL statement

enables the users to query one or more tables to get the information they

want. SQL has only one data query statement SELECT.


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4. Data Control Language (DCL)

The data control language consists of commands that control the users

access to the database objects. Thus DCL is mainly related to the security

issues that are determining who has access to the database objects and what

operations they can perform on them. The task of the DCL is to prevent

unauthorized access to data. The Database Administrator (DBA) has thepower to give and take the privilege to a specific user, thus giving or denying

access to the data. The DCL commands are GRANT and REVOKE.

5. Data Administration Statements (DAS)

Data administration commands allow the user to perform audits and analysis

on operations within the database. They are also used to analyze the

performance of the system. Two data administration command are START

AUDIT and STOP AUDIT. One thing to be remembered here is that, data

administration is totally different from database administration. Database

administration is the overall administration of the database and data

administration is only a subset of that.

6. Transaction Control Statement (TCS)

Transaction control statements are statements, which manage all the

changes made by the DML statements. For example transaction statements

commit data. Some of the transaction control statements are COMMIT,

ROLLBACK, SAVEPOINT and SET TRANSACTION.

VIEWS


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A view is a virtual table, which gives access to a subset of columns from one or

more tables. It is a query stored as an object in the database. Therefore, a view is an

object that derives its data from one or more tables. These tables are referred to as

the base or underlying tables.

A view serves as a security mechanism. It ensures that users are able to retrieve

and modify only the data which is seen by them. The remaining data in the

underlying tables can neither be seen nor accessed. The usage of complex queries

can also be simplified using views. Complex queries can be stored in the form of a

view and data from the view can be extracted using simple queries.

After the view is defined it can be referenced like any other table in the database.

Although a view is similar to a table, it is not stored in the database. It derives its set

of values from the underlying tables.

Syntax of Creating View :-

CREATE VIEW view-name [[column [,column].]]

AS sub query

[WITH CHECK OPTION];

The following figure illustrates the example of the view:-


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Title

Title_Id Title Pub_Id Price

BU2075 You cannotcombat Computer stress

0736 19.99

MC3021 The GourmetMicrowave

0877 2.99

BU7832 Straight Talkabout Computer

1389 19.99

PS2091 Is Anger theEnemy

0736 10.95

TC7777 Sushi, Anyone? 0877 14.99

vwPublisherTitles

Pub_Name Title Price

New Moon Books You cannot combatComputer stress 19.99

Binnet & Hardly The GourmetMicrowave

2.99

Publisher

Pub_Id Pub_Name City State Country

0736 New MoonBooks

Boston MA USA

0877 Binnet &Hardly

Washington DC USA

1389 Algodatainfosystem

Berkeley CA USA


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Algodata Infosystems Straight Talks aboutComputer

19.99

New Moon Books Is Anger the Enemy 10.95

Binnet & Hardly Sushi, Anyone? 14.99

View Derived from the Publishers and Titles Tables.

To get the output, like in the above table, you have to enter the following command:

CREATE VIEW vwPublisherTitles

AS

SELECT Pub_Name, Title, Price FROM Publishers JOIN Titles ON Publishers.Pub_Id= Titles.Pub_Id

The output can be seen using views by entering the following simple SELECT

statement: SELECT * FROM vwPublisherTitles

Views ensure security of data by restricting access to:

Specific rows of table

Specific columns of a table

Specific rows and columns of a table

The rows fetched using joins

The statistical summary of data in a given table


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The subsets of another view or a subset of views and tables

Advantages of Views

Views provide several advantages:

Providing relevant data for users

Hiding data complexity

Organizing data from heterogeneous sources

Reducing the object size.

INDEXES

An index is a structure that provides faster access to the rows of a table based on

the values of one or more columns. The index stores data values and pointers to the

rows where those data values occur. In the index the data values are stored and

stored in the ascending or descending order. So, the RDBMS can quickly search the

index to find a particular data values and hence the row associated with it.


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GUIDELINES FOR INDEX CREATION ARE:-

A column that is often accessed in a sorted order should be indexed so that

the system can take advantage of indexed order.

Columns that are regularly used in joins should be indexed, because the

RDBMS can perform the join faster.

If the number of updates operations (INSERT, UPDATE and DELETE) is more,

compared to the querying operations, then indexing the table will affect

performance, because every time a table is updated, the index also has to be

sorted.

Indexing on columns that have one or two values like gender will not have

any real performance improvement.

Indexing small tables with only a few rows does not improve the

performance.

TYPE OF INDEXES

COMPOSITE INDEX

When an index is made up of more that one column it is called composite index.

Composite index columns do not have to be specified in the same order as in the


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CREATE TABLE statement. You can use any order you want for better performance,

it is a good idea to start with the column that you use most often in searches.

Create index inn_name on Emp(LNAME, FNAME)

UNIQUE INDEX : -

A unique index is one in which no two rows are permitted or in which no duplicate

values are allowed for the same index value. These indexes are usually created on

the primary key of a table. You specify the index as a unique index by using the

keyword UNIQUE. For unique indexes, the RDBMS checks for duplicate values

when the index is created and each time new data is added.

CLUSTERED INDEX : -

Many RDBMS offer you the choice of making your index clustered or non-clustered.

When you create a clustered index, it means that the system will sort the rows of a

table when there is a change made to the index. In non-clustered index, the physical

order of the rows is not the same as their indexed order. There can be as many non-

clustered indexes per table. Clustered indexes are much faster than non-clustered

ones.

USING INDEXES

A unique index on the primary key prevents duplicate and gurantees that every

value in primary key column will infact uniquely identifies the row.


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A column that is often accessed in a sorted order should be indexed so that the

system can take advantage of indexed order.

Command to Dropping an Index

Drop index indexname;

SQL COMMANDSCREATING TABLE : -

Example 1:- The detail about a newspaper that publishes advertisement for


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Tebisco, Inc to be stored in a Recruitment database

Attributes Data

Newspaper code 0001

Newspaper Name Hindustan Times

Region Delhi

Type of Newspaper General

Contact Person Mr. xyz

HO Address Xyz New Delhi-01

City New Delhi

State Delhi

Zip 110001

Country Code 001

Phone (011)2343242

Solution:-

CREATE Statement : -

CREATE TABLE Newspaper

(

cNewspaperCode char(4) NOT NULL,


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cNewspaperName char(20) NOT NULL,

vRegion varchar(20),

vTypeofNewspaper varchar(20),

vContactPerson varchar(35),

vHOAddress varchar(35),cCity char(20),

cState char(20),

cZip char(10),

cCountryCode char(3),

cPhone char(15)

)

2.INSERT Statement :-

Insert statement is used to insert the values in a table. To insert values in above

table, command should be:

INSERT into Newspaper

VALUES (0001 , Hindustan Times , Delhi , General,Mr. xyz, xyz NewDelhi , New Delhi, Delhi, 110001, 001, (011)2343242 )

3. DROP Statement: -

DROP statement is used to remove the table from the database.

DROP TABLE Newspaper

The above command will delete the Newspaper table from the database.

Example 2 :-


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Let us take table named Record

Table: Record

vFirstName vLastName cCity cPhone

Rahul Sharma Delhi 2222222

Sanjay Gupta Punjab 4444444

4. SELECT Statement

SELECT statement can be used to access and retrieve data from the database.

SELECT * from Record

Selecting columns: - SELECT statement can be used to retrieve specific columns

from a table by specifying the column name from the table.

Syntax:

SELECT column_name1[, column_name2,]

FROM table_name

QUERY


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SELECT VFirstName, cCity

FROM Record

The above statement will retrieve VFirstName and cCity from Record

OUTPUT

vFirstName cCity

Rahul Delhi

Sanjay Punjab

5. WHERE StatementWHERE Statement is used with SELECT statement to display the Selected files

from a table.

Syntax:

SELECT column_list FROM table_name

WHERE search_condition

QUERY

SELECT vFirstName, vLastName

FROM Record

WHERE cCity = Delhi

The above query will show the vFirstName and vLastName of record where cCity is


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Delhi

OUTPUT

vFirstName vLastName

Rahul Sharma

EXAMPLE 3:-

ID Title Author Publisher Year Price


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A01 A paintedHouse

Grishan Random House 2001 195.55

A02 Abduction Cook Pan Books 2000 360

A03 Airport Hailey Corgi Books 1968 175.45

B01 Biplane Bach Dell Books 1966 283.35

B02 Bloodline Sheldon Warner Books 1977 100.15

B03 Blue Gold Cussler Simon & Schuster 2000 285

C01 Catch 22 Heller Random House 1994 250.1

D01 Doctors Segal Bantam Books 1988 150

D02 Dragon Cussler Harper Collins 1990 123.55

F01 Flood Tide Cussler Simon & Schuster 1997 414.5

H01 Hawaii Michener Mandarin Books 1959 124.5

H02 Hotel Hailey Corgi Books 1965 175.75

I01 Icon Forsyth Corgi Books 1996 182.35

I02 Illusion Bach Dell Books 1997 330

I03 Inca Gold Cussler Harper Collins 1994 124

I04 Invasion Cook Pan Books 1997 177.9

O01 One Bach Dell Books 1988 289


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P01 Prizes Segal Bantam Books 1995 256.1

S01 Serpent Cussler Simon & Schuster 1999 532.8

S02 Sheba Higgins Signet Books 1995 125

T01 The Class Segal Bantam Books 1985 145.8

T02 TheRunner

Reich Headline Books 2000 199.95

T03 TheSimpleTruth

Baldacci Simon & Schuster 1997 200

T04 Thunder Point

Higgins Signet Books 1993 95.65

T05 Timeline Crichton Centuary Books 1999 623.3

V01 Vector Cook Macmillian 1999 424.8

6.Distinct :

Eliminating Duplicates Select using DISTINCT

SELECT (DISTINCT) Publisher

FROM BOOK;

The result will be the name of the publishers, with no duplicate as shown below:


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Publisher

Bantam Books

Century Books

Corgi Books

Dell Books

Harper Collins

Headline Books

Macmillan

Mandarin Books

Pan Books

Random House

Signet Books

Simon & Schuster

Warner Books

7.Select Using IN:-


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SELECT Title, Author, Publisher, Year

FROM Book

WHERE Year IN(1999,2000)

OUTPUT

Title Author Publisher Year

Abduction Cook Pan Books 2000

Blue Gold Cussler Simon & Schuster 2000

Serpent Cussler Simon & Schuster 1999

The Runner Reich Headline Books 1999

Timeline Crichton Century Books 1999

Vector Cook Macmillan 1999

8. Select Using BETWEEN

BETWEEN can be used to get those items that fall within a range

SELECT Title, Author, Publisher, Price

FROM Book

WHERE Price BETWEEN 400 AND 600;

OUTPUT


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Title Author Publisher Price

Flood Tide Cussler Simon & Schuster 414.5

Serpent Cussler Simon & Schuster 532.8

Vector Cook Macmillan 424.8

9. SELECT using LIKE

Like is very popular clause and also very useful. E.g. if you want to get all the

details of the books whose publishers name starts with S, use LIKE as follows:

SELECT Title, Author, Publisher

FROM Book

WHERE Publisher LIKE S%;

OUTPUT

Title Author Publisher

Blue Gold Cussler Simon & Schuster

Flood Tide Cussler Simon & Schuster

Serpent Cussler Simon & Schuster

Sheba Higgins Signet Books

The Simple Truth Baldacci Simon & Schuster


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10.Ordering While Selecting

For getting the result in a particular order we use thr ORDER BY clause. Consider

the query Get all the distributor details in descending order of discount. The SQL

statement will be as follows:

QUERY

SELECT Title, Author, Publisher, Price FROM Book

WHERE Price>300

ORDER BY Price DESC;

OUTPUT

Title Author Publisher Price

Timeline Crichton Century Books 623.3

Serpent Cussler Simon & Schuster 532.8

Vector Cook Macmillan 424.8

Flood Tide Cussler Simon & Schuster 414.5

Abduction Cook Pan Books 360

Illusion Bach Dell Books 330


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11. AND, OR & NOT

QUERY

SELECT * FROM Book

WHERE ( Year = 1997 OR Price > 200)

AND Publisher IN (Simon & Schuster, Dell Books)

OR Author LIKE C% AND NOT ID = A02;

OUTPUT

ID Title Author Publisher Year Price

B01 Biplane Bach Dell Books 1966 283.35

B03 Blue Gold Cussler Simon & Schuster 2000 285

F01 Flood Tide Cussler Simon & Schuster 1997 414.5

I02 Illusion Bach Dell Books 1997 330

I04 Invasion Cook Pan Books 1997 177.9

O01 One Bach Dell Books 1988 289

S01 Serpent Cussler Simon & Schuster 1999 532.8

T03 The SimpleTruth

Baldacci Simon & Schuster 1997 211

T05 Timeline Crichton Century Books 1999 623.3


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AGGREGATE FUNCTIONS

Consider a table Employee

Empno Name Deptid Basic Hra Deduction Tax

100 Joseph D1 8000 1600 2000 2400

101 Erich D2 6000 1200 0 1500

102 Ken D1 5500 1100 450 1375

103 Tom D1 4800 960 200 1200

104 Jeffrey D2 6400 1280 1400 1920

105 Clive D3 5600 1120 560 1120

106 Robin D4 4700 940 580 940

107 Michael D3 5300 1060 1600 1325

108 Stephen D4 4200 840 0 840

109 Sidney D4 6800 1360 1000 2040

110 Robert D2 7000 1400 1250 2100

111 Jack D1 7500 1500 500 2250


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1. COUNT()

COUNT() is used to count the number of values in a column.

QUERY 1 :- Get the number of employees in the department D1

SELECT COUNT(Name)

FROM Employee

WHERE Deptid = D1

OUTPUT :- 4

QUERY 2 :- Get the number of employees in the department D1 and basic pay lessthan 6000

SELECT COUNT(Name)

FROM Employee

WHERE Deptid = D1

AND Basic < 6000

OUTPUT:- 2

2. SUM()

SUM() is used to find the sum of the values in a column.

QUERY 1:-Find the total basic pay for all the employees in the organization.

SELECT SUM(Basic)

FROM Employee;

OUTPUT:- 71800


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QUERY 2 :- Find the total Basic Pay for all the employees in the department D1

SELECT SUM(Basic)

FROM Employee

WHERE Deptid=D1

OUTPUT:- 25800

3.AVG()

This function is used to find the average of the values in a column.

QUERY 1 :- Find the average HRA of an employee.

SELECT AVG(HRA)

FROM Employee

OUTPUT:- 1196.67

QUERY 2 :- Find the average pay of an employee in the department D1 whose HRA

is greater than 1000.

SELECT AVG(Basic + Hra Deductions Tax)

FROM Employee

WHERE Deptid = D1

AND HRA > 1000

OUTPUT:- 5408.33


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4. MAX() and MIN()

MAX() is used to find the maximum value in a column.

MIN() is used to find the minimum value in a column

QUERY 1:-Find the name of the Employee who gets the maximum basic pay.

SELECT Name

FROM Employee

WHERE Basic = (SELECT MAX(Basic) FROM Employee);

OUTPUT:-

Name

Joseph


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BIBLIOGRAPHY

1. Database Management System

by Alexion Leon and Mathews Leon

2. Database Management System

By Rajesh Narang

3. NIIT Study Material

4. Aptech Study Material

5. Faculty: Mrs. Deepa Gangwani

Documents

Computer File 4th Sem