Whole numbers are a subset of integers, which in turn are a subset of rational numbers.
So, every whole number is an integer, and every integer is a rational number.
So, it is possible for a rational number not to be an integer. Think of any decimal number: 1.356 is a rational number, but it's not an integer.
On the other hand, if a number is not an integer, it can't be a whole number, because all whole numbers are integers.