Task 4 – SQL SELECT DISTINCT

[Mayank GoyalKeymaster]

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

 Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values.The SELECT DISTINCT statement is used to return only distinct (different) values.

 SELECT DISTINCT Syntax

Code:

SELECT DISTINCT [i]column1[/i],[i] column2, …[/i]
FROM [i]table_name[/i];

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Demo DatabaseBelow is a selection from the “Customers” table in the Northwind sample database:SELECT ExampleThe following SQL statement selects all (and duplicate) values from the “Country” column in the “Customers” table:

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Example

Code:

SELECT Country FROM Customers;

Try it Yourself »Now, let us use the DISTINCT keyword with the above SELECT statement and see the result.

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SELECT DISTINCT ExamplesThe following SQL statement selects only the DISTINCT values from the “Country” column in the “Customers” table:Example

Code:

SELECT DISTINCT Country FROM Customers;

Try it Yourself »The following SQL statement lists the number of different (distinct) customer countries:

Code:

SELECT COUNT(DISTINCT Country) FROM Customers;

ExampleTry it Yourself »

 Note: The example above will not work in Firefox and Microsoft Edge! Because COUNT(DISTINCT column_name) is not supported in Microsoft Access databases. Firefox and Microsoft Edge are using Microsoft Access in our examples.Here is the workaround for MS Access:Example

Code:

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

Try it Yourself »

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