Oracle Analytical Function PERCENT_RANK With Example

PERCENT_RANK
------------

PERCENT_RANK is similar to the CUME_DIST (cumulative distribution) function. The range of values returned by PERCENT_RANK is 0 to 1, inclusive. The first row in any set has a PERCENT_RANK of 0. The return value is NUMBER.

As an aggregate function, PERCENT_RANK calculates, for a hypothetical row r identified by the arguments of the function and a corresponding sort specification, the rank of row r minus 1 divided by the number of rows in the aggregate group. This calculation is made as if the hypothetical row r were inserted into the group of rows over which Oracle Database is to aggregate.
The arguments of the function identify a single hypothetical row within each aggregate group. Therefore, they must all evaluate to constant expressions within each aggregate group. The constant argument expressions and the expressions in the ORDER BY clause of the aggregate match by position. Therefore the number of arguments must be the same and their types must be compatible.

As an analytic function, for a row r, PERCENT_RANK calculates the rank of r minus 1, divided by 1 less than the number of rows being evaluated (the entire query result set or a partition).

The following example calculates the percent rank of a hypothetical employee in the sample table hr.employees with a salary of $15,500 and a commission of 5%:

SELECT PERCENT_RANK(15000, .05) WITHIN GROUP
       (ORDER BY salary, commission_pct) "Percent-Rank" 
  FROM employees;

Percent-Rank
------------
  .971962617

Analytic Example

The following example calculates, for each employee, the percent rank of the employee's salary within the department:

SELECT department_id, last_name, salary, PERCENT_RANK() 
       OVER (PARTITION BY department_id ORDER BY salary DESC) AS pr
  FROM employees
  ORDER BY pr, salary, last_name;

DEPARTMENT_ID LAST_NAME                     SALARY         PR
------------- ------------------------- ---------- ----------
           10 Whalen                          4400          0
           40 Mavris                          6500          0
              Grant                           7000          0
. . .
           80 Vishney                        10500 .181818182
           80 Zlotkey                        10500 .181818182
           30 Khoo                            3100         .2
. . .
           50 Markle                          2200 .954545455
           50 Philtanker                      2200 .954545455
           50 Olson                           2100          1
. . .