Final answer:
The SQL query retrieves last names from both 'hourly' and 'salaried' tables without eliminating duplicates, resulting from the use of UNION ALL.
Step-by-step explanation:
The SQL query in question is combining the results from two different tables using the UNION ALL operator. The query is:
SELECT lname FROM hourly UNION ALL SELECT lname FROM salaried;
This query will produce a result set that includes the lname field from both the hourly and salaried tables. The key characteristic of UNION ALL is that it does not eliminate duplicate rows, meaning if the same last name appears in both tables, it will appear twice in the results. On the contrary, if the UNION operator were used instead, it would combine the results and remove duplicates, showing each last name only once regardless of how many times it appears across both tables.
The result of the SQL query SELECT lname FROM hourly UNION ALL SELECT lname FROM salaried; is the combination of the lname column from the hourly table and the lname column from the salaried table.
For example, if the hourly table has the lname column with values 'Smith' and 'Johnson', and the salaried table has the lname column with values 'Doe' and 'Brown', the result of the query would be 'Smith', 'Johnson', 'Doe', 'Brown'.
The UNION ALL operator combines the results of both queries, including any duplicate values.