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.

Oracle DISTINCT Example: (with single expression)

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:

Oracle DISTINCT Example: (with multiple expressions)

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.