PERCENT_RANK assigns a percentile ranking between 0 and 1 (inclusive) to each row. Percentile rankings indicate the percentage of data that are at or below a certain value within a group. These ranks can include duplicate values if multiple rows contain the same value for the window function field.
The following example calculates the percentile rank of each employee based on their salary within each department:
SELECT PERCENT_RANK() OVER (PARTITION BY Department ORDER BY Salary) FROM Company.Employee