Functions
The window function can be any of the aggregation functions that we discussed above.
- Special window functions
ROW_NUMBER()→ # of the current rowRANK()→ Order position of the current row.
The OVER keyword specifies how to group together tuples when computing the window function.
Use PARTITION BY to specify group.
SELECT cid, sid,
ROW_NUMBER() OVER (PARTITION BY cid)
FROM enrolled
ORDER BY cid
SELECT *,
ROW_NUMBER() OVER (ORDER BY cid)
FROM enrolled
ORDER BY cid