Is the statement “A join of two datasets can result in fewer rows in the joined result” true or false?

The statement "A join of two datasets can result in fewer rows in the joined result" is indeed true. This can occur when using certain types of joins, most notably an inner join. An inner join produces a result set that includes only the rows where there is a match between the two datasets based on the specified join condition. If there are rows in either dataset that do not meet this condition, they will be excluded from the resultant dataset.

For instance, if one dataset has 100 rows and another has 200 rows, but only 50 rows meet the join condition, the result will contain only those 50 rows. Thus, it is common for joins to lead to a reduction in the row count, particularly when there are mismatches between the datasets or when an inner join is employed.

In contrast, other types of joins, like outer joins, may result in the combined dataset having more rows or at least keeping all the rows from one or both datasets, potentially increasing the total count.