16. DISTINCT and its counterpart, ALL, can be used more than once in a SELECT statement.

A. True
B. False

17. The result of every SQL query is a table.

A. True
B. False

18. COUNT(field_name) tallies only those rows that contain a value; it ignores all null values.

A. True
B. False

19. SUM, AVG, MIN, and MAX can only be used with numeric columns.

A. True
B. False

20. Most companies keep at least two versions of any database they are using.

A. True
B. False