Oracle DISTINCT Clause
Oracle DISTINCT clause is used to remove the duplicate records from the result set. It is only used with SELECT statement.
Syntax:-
  
    SELECT DISTINCT expressions  
    FROM tables  
    WHERE conditions;  


Example:- We create table named with Employee and insert some records as shown in below:
  
   CREATE TABLE Employee  
    (
    Empcode varchar2(30) primary key,
    Name varchar2(100),
    Age number(5),   
    Salary numeric(10,2),
    Email varchar2(200),   
    State varchar2(100)  
    CONSTRAINT Employee_pk PRIMARY KEY (Empcode)  
    );  


    //Insert some records as shown below:-

Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1001','Santosh Kumar Singh',22,12000,'s@gmail.com','Bihar')
Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1002','Reena kumari',25,15000,'r@gmail.com','Bihar')
Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1003','Anu Singh',21,14000,'a@gmail.com','UP')
Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1004','Gagan Agrawal',24,11000,'g@gmail.com','Haryana')
Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1005','Suraj',21,13000,'su@gmail.com','Bihar')
Insert into Employee(Empcode,Name,Age,Salary,Email,State) values('Emp1006','Pramod kumar sah',27,14000,'pk@gmail.com','New Delhi')



Execute this query:- In the above table Employee state such as Bihar many time entry. When we use Distinct clause then get following output.
  
select distinct State from Employee