SQL | Distinct Clause

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

Syntax :

SELECT DISTINCT column1, column2 
FROM table_name 

column1, column2 : Names of the fields of the table.

table_name : Table from where we want to fetch the records.

This query will return all the unique combinations 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. 

Table – Student

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
3	SUJIT	ROHTAK	XXXXXXXXXX	20
2	RAMESH	GURGAON	XXXXXXXXXX	18

Queries

• To fetch unique names from the NAME field –
  

SELECT DISTINCT NAME 
FROM Student;

Output : 

NAME
Ram
RAMESH
SUJIT
SURESH

• To fetch a 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

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.

This article is contributed by Harsh Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks. 

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