To combine two tables in a database while removing duplicate rows, which SQL operator should be used?

The correct choice is the UNION operator, which is specifically designed to combine the results of two or more SQL queries while automatically removing any duplicate rows from the final result set. When you use UNION, the database engine performs a distinct operation on the combined set, ensuring that each row in the output is unique.

This behavior is particularly useful when aggregating data from different sources or tables where overlap or redundancy might exist, as it streamlines the results and presents a cleaner, more consolidated view. Additionally, the SQL standard dictates that UNION will sort through the combined set to enforce this uniqueness.

On the other hand, while JOIN is used to combine related rows from two or more tables based on a related column, it does not inherently deal with duplicates across the sets, as it simply merges rows according to specified conditions. The NESTED WITH clause is not a standard SQL operator for combining tables, and its application is related to creating derived tables or common table expressions, which is different from combining rows directly in the context described. UNION ALL, although it combines the results of multiple queries, does not remove duplicates; instead, it includes all records from each query, including duplicates. Thus, using UNION is the correct choice when the goal is to eliminate redundancy in the