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What is the SQL DISTINCT keyword?

• The SQL DISTINCT keyword is used in conjunction with the SELECT statement to remove all duplicate records and only return unique records.
• DISTINCT can also be used in conjunction with aggregate SQL functions such as COUNT, MAX, SUM, AVG, and so on.
• DISTINCT operates not only on a single column of a table but also on multiple columns of a table, with DISTINCT in SQL eliminating rows where all the selected columns are identical.

Syntax:

SELECT DISTINCT column1, column2,.....columnN 
FROM table_name
WHERE [condition]

Example:

Consider a Student record:

Roll No	Name	Age	Country	Course
101	John	18	America	MBA
102	Sam	16	America	Aerospace
103	Sherry	18	Japan	MBBS
104	Harold	23	Korea	MTech

SELECT DISTINCT Country FROM Students;

The above query will return the Distinct country names.

Output:

Country

America

Japan

Korea

Note: there’s a single America because we used the DISTINCT keyword.

Note: also read about SQL: HAVING Clause

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