How to use DISTINCT in SQL

Problem

You want to select unique rows from a SQL table by eliminating duplicate data entries.

Sample data

Consider we have a table called 'Employees' with the following data:

Solution

The DISTINCT clause is used to remove duplicate values from the result set of a SELECT statement in SQL.

MySQL Solution

SELECT DISTINCT name, job_title FROM Employees;

PostgreSQL Solution

SELECT DISTINCT name, job_title FROM Employees;

Explanation

The DISTINCT clause works the same way in both MySQL and PostgreSQL. When applied, it ensures that the result set of the SELECT statement only includes unique rows.

In our example, the SQL statement selects unique combinations of 'name' and 'job_title' from the 'Employees' table. After executing the above SQL statement, you'll get the following result:

As you can see, duplicate rows are eliminated from the result set. John, who appeared twice as a 'Developer', now only appears once. The same goes for Mary as a 'Designer'.