SQL commands

1. SQL
Structured Query Language

2. SQL is language use for creating, accessing and
manipulating database systems. SQL statements are used
to retrieve and update data in a database. SQL works with
database programs like MS Access, DB2, Informix, MS SQL
Server, Oracle, Sybase, etc.
Database is collection of data Stored in table format.
Each table is identified by a name . Tables contain records
(rows) and columns.
Below is an example of a table called “employee":
Id Name Sal
1 Aditya 25000
2 Vaidehi 17000

3. For Performing Operations on the data stored in
tables different commands are available in sql.
SQL commands are categorized in different groups
DDL : Data Definition Language
DML: Data Manipulation Language
TCL : Transaction Control Language

4. DATA DEFINITION LANGUAGE(DDL)
DDL include three commands
•CREATE - Creates a new database table or object.
• ALTER - Alters (changes) a database table or Object
We can Add ,Modify and Drop column
• DROP - Deletes a database table or Object

5. Create
Syntax:
Create table table_name( column1 datatype(size),
column2 datatype(size),
.
.
columnn datatype(size));
Example:
Create table Employee(id number(3),
name varchar2(10),
salary number(10));

6. EFFECT OF CREATE COMMAND
Id Name salary

7. Alter
Syntax:
Alter table table_name
ADD/MODIFY/DROP (column specification);
Example
Alter table employee Add (Address varchar2(10));
Alter table employee modify(Address varchar2(12));
Alter table employee Drop(Adress );

8. EFFECT OF ALTER COMMAND
ID NAME SALARY
Alter table employee Add (Address varchar2(10));
ID NAME SALARY ADDRESS
Alter table employee Drop(Address );
ID NAME SALARY

9. Drop
Syntax:
Drop table table_name;
Example:
Drop table employee;

10. DATA MANIPULATION LANGUAGE (DML)
Data Manipulation Language (DML) include
select,update,delete,insert:
•SELECT - Use for retrieving data from a database table
•UPDATE – Use for updating data in a database table
•DELETE – Use for deletes data from a database table
•INSERT - Use for inserts new data into a database table

11. SELECT STATMENT
Syntax
Select * or column1,column2..column n from table_name
[where condition];
Example
Select * from employee;
Select name from employee;

12. INSERT STATMENT
Syntax
INSERT INTO table_name[(column1,column2,…)]
VALUES (value1, value2,....) ;
Example;
Insert into emp(id,name,salary)values(101,’Aditya’,100000);
Id Name Sal
1 Aditya 100000
2 Vaidehi 17000

13. UPDATE STATMENT
Syntax
UPDATE table_name
SET column_name = new_value
WHERE column_name = some_value;
Example:
update emp
set salary=50000
where id=101;
Id Name Sal
101 Aditya 50000
102 Vaidehi 17000

14. DELETE STATMENT
Syntax
DELETE FROM table_name
[WHERE column_name = some_value ]
Example:
delete from employee
where id=101;
Id Name Sal
102 Vaidehi 17000

15. Thank you!