Explain the difference between RANK(), DENSE_RANK(), and ROW_NUMBER() window functions.

Assigns the same rank to rows with identical values in the ORDER BY clause (ties).

Leaves gaps in the ranking sequence after ties.

Useful when you want to reflect tie positions explicitly.

Assigns the same rank to tied rows, similar to RANK().

Does not leave gaps in the ranking sequence.

Useful when you want consecutive ranking numbers even with ties.

ROW_NUMBER() always gives unique numbers; ignores ties.

RANK() gives tied rows the same rank and skips subsequent numbers.

DENSE_RANK() gives tied rows the same rank but does not skip numbers.