SELECT 'T' AS result
FROM Book
HAVING MIN(NumberOfPages) < MAX(NumberOfPages);
Despite the absence of the DISTINCT keyword, the query will never return more than one row. If the HAVING clause is satisfied then the result will be a single row with a single column containing the value 'T' (indicating we have books with differing numbers of pages), otherwise the result will be the empty set i.e. zero rows with a single column.