7.23 Window functions
Using a window function, you can specify a range of rows derived from the results of a table expression, and then determine aggregated values for the rows in that range.
The window functions are shown in the following table:
|
No. |
Window function |
Description |
|---|---|---|
|
1 |
RANK |
Determines the ranking of the rows in an ordered set of rows. The ranking values might not be contiguous integer values. |
|
2 |
DENSE_RANK |
Determines the ranking of the rows in an ordered set of rows. The ranking values will be contiguous integer values. |
|
3 |
CUME_DIST |
Determines the relative position of a row in an ordered set of rows. The CUME_DIST of row R is the number of rows that are in front of R in the window (partition) or that have the same sort key value as R, divided by the number of rows in the window (partition) of R. |
|
4 |
ROW_NUMBER |
Assigns a unique number to each row in an ordered set of rows. |
|
5 |
Set function |
Determines the value of a set function with respect to a window frame. |