Question

Suppose your company stores EMPLOYEE and CUSTOMER data in separate tables. If you want to find all customers who are not also employees, which SQL keyword would you most likely use?

a) UNION

b) UNION ALL

c) EXCEPT

d) INTERSECT

Answer 1

The correct SQL keyword to find all customers who are not also employees is EXCEPT. (option c)

Step-by-step explanation:

To find all customers who are not employees in separate tables, you would most likely use the SQL keyword EXCEPT. The EXCEPT keyword is used to retrieve the distinct rows from the result set of the first SELECT query that is not present in the result set of the second SELECT query. In this context, the first query could be selecting all records from the CUSTOMER table, and the second query could be selecting all records from the EMPLOYEE table.

The other options, UNION, UNION ALL, and INTERSECT, are not suitable for this specific requirement. UNION and UNION ALL are used to combine the results of two or more SELECT statements, while INTERSECT is used to retrieve the common records between two SELECT statements. None of these options directly address the need to find customers who are not employees.

For the specific task of finding customers who are not employees, the correct SQL keyword is EXCEPT, as it allows you to exclude records present in another table's result set from your query result.