Ranking
Ranking functions assign a rank to each row within a partition of a result set.
Functions
ROW_NUMBER(): Unique number for each row.RANK(): Same rank for ties, leaves gaps.DENSE_RANK(): Same rank for ties, no gaps.
Example
Ranking airports by worst average delays:
SELECT airport_name, avg_delay,
RANK() OVER (ORDER BY avg_delay DESC) as delay_rank
FROM airport_metrics;