Sql Fundamentals Notes

Introduction to computers: Presentation’s URL
http://www.authorstream.com/Presentation/devanraju80-221913-introducation-computers-unit-education-ppt-powerpoint/ introduction to network technologies:- Presentation’s URL http://www.authorstream.com/Presentation/devanraju80-224863-introduction-network-technologies-tech-education-ppt-powerpoint/ HTML in 15 minits :- http://www.authorstream.com/Presentation/devanraju80-248988-html-15-min-lang-education-ppt-powerpoint/ Evolution of computers: http://www.authorstream.com/Presentation/devanraju80-488065-evolution1/

SQL

SQL COMMANDS

DDL (DATA DEFINATION LANGUAGE):-

DDL commands are used to create and remove database objects.

The commands are Create, Alter and Drop.

Create Command:-

This command is used to create the table.

Syntax:-create table

(col name datatype(w),col name data type(w));

Example: - create table aparna(sno number(2),name varchar2(10),m1 number(3), m2 number(3));

Rules:

1. Table name should not be a oracle reserved words.
2. It is not case sensitive; we can use upper and lower case.
3. Table name should start with character.
4. The length of the table name should be below 32 characters.

Alter command:-

This command is used to add a new column and to change the width of the column.

Syntax: - alter

modify/add ;

Example: - alter table aparna add m3 number (3);

Alter table aparna modify name varchar2 (20);

Drop commad:-

This command is used to delete the table.

Syntax: - Drop table

Example: - drop table aparna.

DCL (DATA CONTROL LANGUAGE):-

DCL commands are used to control the kind of data access to the database and also for transaction control.

The commands are Commit, Rollback, Save point.

Commit command:-

This command is used to save the transactions.

Syntax:- commit

Example:-commit

Rollback command:-

This command is used to scroll back the record (previous operations) only DCL commands. This command is exactly opposite of the commit command.

Syntax: - rollback

Example: - rollback.

Savepoint command: -

This command is used to saves the current point in the processing of a transaction. It is just like book mark in ms word.

Syntax: - savepoint

DML (DATA MANIPULATE LANGUAGE):-

DML commands are used for data manipulation.

The commands are Select, Insert, Update and Delete.

Select command: -

This command is used to retrieve the row from the database files.

Syntax: - select * from

Example:- select * from rama.

Insert command:-

This command is used to insert records in to the table.

Syntax: - insert into

values

Example: - insert into rama (sno, name, m1, m2, m3) values (&sno,’&name’, &m1,&m 2, &m 3);

Update command:-

This command is used to update the database records

Syntax: - update

set =number;

Example: - update emp set comm=sal*100;

Delete command:-

This command is used to delete the records from the data base.

Syntax: -delete from

where

Example: - delete from emp where sal>=500;

Note: - where clause is used to give conditions.

TCL (TRANCTION CONTROL LANGUAGE)

TCL commands are Grant and Invoke.

Grant command: -

This command is used to give access to the database that to grant permissions for the DML, DCL commands

Revoke command:-

This command is used to get back the given grant permission.

OTHER STANDARD COMMANDS:-

1. Select * from tab;

This sql statement is used to get the list of tables.

2. Select * from tab;

This command is used to view the information of the current user.

3. Desc command:-

This command is used to display the structure of the table.

Syntax: - desc table name;

Example: - desc table rama;

These two Exercise can be easily done by practicing the above all commands

Exercise-25

Execute any six Sql commands

Exercise-26

Design a database in Sql for the sale receipt of medicines with the following columns:-

Sno, Name of the product, Quantity, cost. Enter 5 different medicines and display the reports

devanraju pericherla