What technique would you use to ensure there are no duplicate entries in the result set of a SELECT statement?

The technique that ensures there are no duplicate entries in the result set of a SELECT statement is the use of the UNION operator. The UNION operator combines the results of two or more SELECT statements and automatically removes any duplicate rows from the final result set. This enables you to retrieve a distinct set of records, providing a clean output without any redundancy.

In scenarios where maintaining duplicates is acceptable or necessary, UNION ALL would be used instead, as it combines the results and includes all records, regardless of any duplicates. LEFT OUTER JOIN and INNER JOIN are types of joins that are used to combine rows from two or more tables based on a related column. However, they do not inherently filter out duplicates from the final result set, which is the primary aim of the question.