SQL (Structured Query Language) is a programming language for managing relational databases that includes various command types such as Data Definition Language (DDL), Data Manipulation Language (DML), Data Control Language (DCL), Transaction Control Language (TCL), and Data Query Language (DQL). DDL commands define and modify database structures, while DML commands are used for data manipulation, and DCL commands manage user permissions. TCL handles transactions, and the primary DQL command, 'select', retrieves data based on specified conditions.

2. Introduction to SQL:-
•Structured query language (SQL) is a
programming language for storing and
processing information in a relational
database.
•-> A relational database stores
information in tabular form, with
rows and columns representing
different data attributes and the
various relationships between the data

3. VARIOUS TYPES OF SQL COMMANDS:-
1.Data Definition Language(DDL)
2.Data Manipulation Language(DML)
3.Data Control Language(DCL)
4.Transaction Control Language(TCL)
5.Data Query Language(DCL)

4. FLOW CHART:

5. Data Definition Language:-
• DDL (Data Definition Language) is a type of SQL
command used to define data structures and
modify data. These commands are used to create or
modify the tables in SQL.
• DDL COMMANDS:
1.Create
2.Alter
3.Truncate
4.Drop
5.Rename

6. 1.CREATE COMMAND:-
This command is used to create a new table in SQL. The
user has to give information like table name, column names,
and their datatypes.
SYNTAX:
CREATE TABLE table-name
(column1 data-type(size),
column2 data-type(size),
………………
column N data-type(size));
Ex: create table student( sno number(3),
sname varchar2(10),
saddress varchar2(10));

7. 2. ALTER COMMAND:-
•To change the structure of a table. This change could
be either modify an existing attribute or add a new
attribute.
• SYNTAX:
ALTER TABLE table-name {ADD / MODIFY} (column1
datatype1);
• Ex1: alter table stu add (sname varchar2(15));
• Ex2: alter table stu modify(sname char(6));

8. 3.TRUNCATE COMMAND:-
To remove all rows from a table we can use ‘truncate’
command.
•SYNTAX: TRUNCATE TABLE <tablename>
Ex: TRUNCATE table stu;
4.DROP COMMAND:-
The drop command can be used to drop a table.
SYNTAX: DROP TABLE table_name;
Ex: drop table stu;

9. 5.RENAME COMMAND:-
Rename command can be used to change the
name of an exiting table.
SYNTAX: RENAME <old name> to <new name>;
Ex: rename stu to student;

10. DATA MANIPULATION LANGUAGE:-
• A data manipulation language (DML) is a
computer programming language used for
adding , deleting, and modifying data in a
database.
•DML COMMANDS:
•1.Insert
•2.Update
•3.Delete
•4.Merge

11. INSERT COMMAND:-
The insert command is used to add rows to a table .
SYNTAX: insert into <tablename> values(a list of data values):
Ex: insert into student values (101, ‘brahmam’, ‘gnt’);
2.UPDATE COMMAND:-
An update statement changes the data of one or more records in a
table.
SYNTAX: update table_name SET column1 = value1, column2 =
value2,… WHERE condition;
Ex: UPDATE customers SET contact name = ‘Vishnu’, city = ‘viz’
WHERE customer id =1;

12. DELETE COMMAND:-
• The delete statement is used to remove one or more
records from a table.
• SYNTAX:
DELETE FROM table_name WHERE condition;
• Ex:
delete from customer where customer name = ‘Vishnu’;

13. DATA CONTROL LANGUAGE (DCL):-
• DCL commands are used to enforce database security in a
multiple user database environment.
• Only Database Administrator’s or owners of the database
object can provide /remove privileges on a database object.
• Two types of DCL commands. They are,
GRANT COMMAND
 REVOKE COMMAND

14. GRANT COMMAND:-
• GRANT is a command used to provide access or privileges on
the database objects to the users.
• SYNTAX: grant privileges on <object name> to <user name>;
Ex:GRANT SELECT, UPDATE ON MY_TABLE TO SOME_USE
R, ANOTHER_USER;
•  REVOKE COMMAND:- The REVOKE command user access
rights or privileges to the database objects.
• SYNTAX: revoke privileges on <object name> from <user
name>;
• Ex:
REVOKE SELECT, UPDATE ON MY_TABLE FROM U
SER1, USER2;

15. TRANSACTION CONTROL LANGUAGE(TCL):-
• Transaction changes can be made permanent to a database
only if they are committed. A transaction executable
statements and end explicitly with their rollback or commit
statement and implicity.
Commit
Rollback
Save point

16. CON…
• COMMIT:- Commit command is used to save all the
transactions to the database.
• SYNTAX: COMMIT;
• Rollback:- Rollback command is used to undo transactions
that have not already been saved to the database.
• SYNTAX: ROLLBACK;
• Ex: delete from customers where age =25;
• ROLLBACK;
• SAVEPOINT:- It is used to roll the transaction back to a
certain point without rolling back the entire transaction.
• SYNTAX: SAVEPOINT savepoint_name;

17. DATA QUERY LANGUAGE(DQL):-DQL is used
to fetch the data from the database
• It uses only one command i.e, SELECT
• SELECT: This is the same as the projection
operation of relational algebra. It is used to
select the attribute based on the condition
described by WHERE clause.
1.SYNTAX:SELECT expressions
2.FROM TABLES
3.WHERE conditions;
Ex: SELECT emp_name
FROM employee
WHERE age > 20;