# PERCENT_RANK

Returns the percent rank of the current row within the partition as specified by the order by clause.

The result is calculated with the following formula: `(rank - 1)/(total_rows - 1)`

## Syntax

``````PERCENT_RANK () OVER (
[PARTITION BY (col | expr), ...]
[ORDER BY (col | expr), ...]
)``````

## Return Type

A `DOUBLE` data type.

## Examples

```CREATE TABLE pr_example (a int, b int);
INSERT INTO pr_example VALUES(1,2),(2,2),(3,3),(4,3);```
`SELECT a,b, PERCENT_RANK() OVER(ORDER BY a,b) FROM pr_example;`
``````+------+------+-----------------------------------+
| a    | b    | percent_rank() over(order by a,b) |
+------+------+-----------------------------------+
|    1 |    2 |                                 0 |
|    2 |    2 |                0.3333333333333333 |
|    3 |    3 |                0.6666666666666666 |
|    4 |    3 |                                 1 |
+------+------+-----------------------------------+``````
`SELECT a,b, PERCENT_RANK() OVER(ORDER BY b) FROM pr_example;`
``````+------+------+---------------------------------+
| a    | b    | percent_rank() over(order by b) |
+------+------+---------------------------------+
|    1 |    2 |                               0 |
|    2 |    2 |                               0 |
|    3 |    3 |              0.6666666666666666 |
|    4 |    3 |              0.6666666666666666 |
+------+------+---------------------------------+``````