SQL | Distinct Clause

The distinct keyword is used in conjunction with select keyword. It is helpful when there is need of avoiding the duplicate values present in any specific columns/table. When we use distinct keyword only the unique values are fetched.

Basic Syntax:

SELECT DISTINCT column1,column2 FROM table_name 
column1 , column2: names of the fields of the table
table_name: from where we want to fetch

This query will return all the unique combination of rows in the table with fields
column1 , column2. 

NOTE: If distinct keyword is used with multiple columns, the distinct combination is displayed in the result set.

Queries

• To fetch unique names from the NAME field

  SELECT DISTINCT NAME FROM Student;

  Output:

  NAME
  Ram
  RAMESH
  SUJIT
  SURESH

• To fetch unique combination of rows from the whole table

  SELECT DISTINCT * FROM Student;

  Output:

  ROLL_NO	NAME	ADDRESS	PHONE	Age
  1	Ram	Delhi	XXXXXXXXXX	18
  2	RAMESH	GURGAON	XXXXXXXXXX	18
  3	SUJIT	ROHTAK	XXXXXXXXXX	20
  4	SURESH	Delhi	XXXXXXXXXX	18

  Please note: Without the keyword distinct in both the above examples 6 records would have been fetched instead of 4, since in the original table there are 6 records with the duplicate values.

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