What is the function of the DISTINCT operator in SQL and how does it affect the query results?

The DISTINCT operator in SQL is used to select unique values from a column or set of columns. It removes duplicates from the query result, returning only unique rows.

For example, if a table has multiple records with the same value in the city column, the query:

SELECT DISTINCT city FROM users;

will return a list of unique cities without repetitions.

Thus, DISTINCT affects the query results by reducing the number of rows through the exclusion of duplicate values.