We have numerous methods to deal with ranking problem in SQL , but the desired one should be based on what we actually want.
Ranking is a process to assign a position in a hierarchy or scale. Now it is our wish and requirment how we like to rank. Either we want to rank all with same value on same rank and next one to the next or we want all with one value at one rank and next value to the rank number after the total number of previous rank or we like to bind up all with in 0 to 1 value.
Business requirment and need is going to decide the ranking method.