SQL DISTINCT clause with examples.
SQL DISTINCT clause is used to remove duplicates from the result set of a SELECT statement.
The syntax for the SQL DISTINCT clause is:
SELECT DISTINCT expressions FROM tables WHERE conditions;
expressions are the columns.
tables are the tables that you wish to retrieve records from..
conditions are conditions that must be met for the records to be selected.
EXAMPLE - WITH SINGLE FIELD
the simplest SQL DISTINCT query example. the SQL DISTINCT clause to return a single field that removes the duplicates from the result set.
SELECT DISTINCT designation FROM employee;
This SQL DISTINCT example would return all unique designation values from the employee table.
EXAMPLE - WITH MULTIPLE FIELDS
How you might use the SQL DISTINCT clause to remove duplicates from more than one field in your SQL SELECT statement.
SELECT DISTINCT designation, location FROM employee;
This SQL DISTINCT clause example would return each unique designation and location combination. In this case, the DISTINCT applies to each field listed after the DISTINCT keyword.