SQL SELECT DISTINCT Statement

The SQL SELECT DISTINCT Statement

The SELECT DISTINCT statement is used to return only distinct (different) values.

Select all the different countries from the "Customers" table:

SELECT DISTINCT Country FROM Customers;

Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values.

SELECT DISTINCT column1, column2, ... FROM table_name;

Below is a selection from the Customers table used in the examples:

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	05021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	05023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden

If you omit the DISTINCT keyword, the SQL statement returns the "Country" value from all the records of the "Customers" table:

SELECT Country FROM Customers;

By using the DISTINCT keyword in a function called COUNT, we can return the number of different countries.

SELECT COUNT(DISTINCT Country) FROM Customers;

Note: The COUNT(DISTINCT column_name) is not supported in Microsoft Access databases.

Here is a workaround for MS Access:

SELECT Count(*) AS DistinctCountries
FROM (SELECT DISTINCT Country FROM Customers);

You will learn about the COUNT function later in this tutorial.