The SQL SELECT DISTINCT Statement
The SELECT DISTINCT statement is used to return only distinct (different) values.
Example
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.
Syntax
SELECT DISTINCT column1, column2, ... FROM table_name;
Demo Database
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 |
SELECT Example Without DISTINCT
If you omit the DISTINCT keyword, the SQL statement returns the “Country” value from all the records of the “Customers” table:
Example
SELECT Country FROM Customers;
Count Distinct
By using the DISTINCT keyword in a function called COUNT, we can return the number of different countries.
Example
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:
Example
SELECT Count(*) AS DistinctCountries
FROM (SELECT DISTINCT Country FROM Customers);