Friday, 5 October 2012

The SQL SELECT DISTINCT Statement

The SQL SELECT DISTINCT Statement

In a table, some of the columns may contain duplicate values. This is not a problem, however, sometimes you will want to list only the different (distinct) values in a table.

The DISTINCT keyword can be used to return only distinct (different) values.

SQL SELECT DISTINCT Syntax

SELECT DISTINCT column_name(s)

FROM table_name

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SELECT DISTINCT Example

The "Persons" table:


P_Id    LastName    FirstName    Address    City
Hansen    Ola    Timoteivn 10 Sandnes
2    Svendson    Tove    Borgvn 23 Sandnes
3    Pettersen    Kari    Storgt 20  Stavanger


Now we want to select only the distinct values from the column named "City" from the table above.

We use the following SELECT statement:

SELECT DISTINCT City FROM Persons

The result-set will look like this:
City
Sandnes
Stavanger
Stavanger

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