What window functions have you used most often? How does RANK differ from DENSE_RANK?

Window functions are most commonly used in analytics for ranking, aggregation, and calculating moving metrics.

• RANK() assigns a rank to rows within a window, giving the same rank to identical values, and creating gaps in ranks if there are duplicates. For example, if two rows share rank 1, the next will be rank 3.

• DENSE_RANK() is similar to RANK(), but ranks are consecutive without gaps. If two rows have rank 1, the next will be rank 2.

Example:

Value	RANK()	DENSE_RANK()
100	1	1
100	1	1
90	3	2
80	4	3

Thus, DENSE_RANK is useful when continuous ranking is important, while RANK accounts for gaps due to duplicates.