SQL Select Distinct
The SQL SELECT DISTINCT Statement
To retrieve just distinct (different) data, use the SELECT DISTINCT command.
Example
Select all the different countries from the “Customers” table:
SELECT DISTINCT Country FROM Customers;
A column in a database may have a lot of duplicate entries, and there may be instances when you just want to list the unique values.
Syntax
SELECT DISTINCT column1, column2, …
FROM table_name;
Demo Database
| 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
The SQL statement returns the “Country” value from each record in the “Customers” table if the DISTINCT clause is left out:
Example
SELECT Country FROM Customers;
Count Distinct
We may retrieve the total number of distinct countries by utilizing the DISTINCT keyword in the COUNT function.
Example
SELECT COUNT(DISTINCT Country) FROM Customers;
Note: Microsoft Access databases do not support COUNT(DISTINCT column_name).
An MS Access workaround is provided here:
Example
SELECT Count(*) AS DistinctCountries
FROM (SELECT DISTINCT Country FROM Customers);
The COUNT function will be covered later in this tutorial.
