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;

Parameters:

expressions:It specifies the columns that you want to retrieve.

tables: It specifies the table from where you want to retrieve records.

conditions: It specifies the conditions that must be fulfilled.

Let's take a table "customers"

Customer table:

CREATE TABLE  "CUSTOMERS" 
   (	"NAME" VARCHAR2(4000), 
	"AGE" NUMBER, 
	"SALARY" NUMBER, 
	"STATE" VARCHAR2(4000)
   )
/

Execute this query:

SELECT DISTINCT state
FROM customers
WHERE name = 'charu';

Output:

Execute this query:

SELECT DISTINCT name, age, salary
FROM customers
WHERE age >= '60';

Output:

This example specifies distinct name, age and salary of the customer where age is greater than or equal to 65.