SQL SELECT DISTINCT

The SQL SELECT DISTINCT Statement

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

Retrieve the distinct countries listed in the “Customers” table.

SELECT DISTINCT Country FROM Customers;

In a table, a column frequently comprises numerous repetitive values; occasionally, you may seek to display only the unique (distinct) values.

SELECT DISTINCT column1, column2, ...

 FROM table_name;

Here is a segment from the Customers table employed in the illustrations:

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

Without including the DISTINCT keyword, the SQL query will retrieve the “Country” value from every record in the “Customers” table.

SELECT Country FROM Customers;

Employing the DISTINCT keyword within the COUNT function allows us to retrieve the count of unique countries.

SELECT COUNT(DISTINCT Country) FROM Customers;

Please note that the COUNT(DISTINCT column_name) function is not compatible with Microsoft Access databases.

Here is a workaround for MS Access:

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

Later in this tutorial, you’ll gain insight into the COUNT function.