PERCENT_RANK aggregate function
The PERCENT_RANK function returns the relative percentile rank of a row that is hypothetically inserted into a group of rows.
The schema is SYSIBM.
 expression
 An expression that specifies a row that is hypothetically inserted into a group of rows. The expression must return a value that is a builtin data type. The expression must be a constant, a variable, or a cast of a constant or variable (SQLSTATE 428I9).
 orderbyclause

 ORDER BY
 Specifies the order of the rows from the same grouping set that are processed in the aggregation.
 sortkey
 The sort key can be a column name or a sortkeyexpression. If the sort key is a constant, it does not refer to the position of the output column. A constant implies no sort key, unlike a constant in the ordinary ORDER BY clause.
 ASC
 Uses the values of the sortkey in ascending order.
 DESC
 Uses the values of the sortkey in descending order.
 NULLS FIRST
 The ordering considers null values before all nonnull values in the sort order.
 NULLS LAST
 The ordering considers null values after all nonnull values in the sort order.
The number of expressions must be the same as the number of sortkey expressions (SQLSTATE 42822). The data type of each expression and the data type of the corresponding sortkey expression must be compatible (SQLSTATE 42822).
The data type of the result is DECFLOAT(34). The actual result is greater than 0.0 and less than or equal to 1.0.
Example
Set the host variable PR to the relative percentile rank of a hypothetical new employee's salary
of 47000 within the salaries of the employees in department
'A00'.
SELECT PERCENT_RANK(47000) WITHIN GROUP (ORDER BY SALARY)
INTO :PR FROM EMPLOYEE WHERE WORKDEPT = 'A00'
PR
is set to a value of 0.4. The following result set is shown for
reference.
SELECT SALARY FROM EMPLOYEE WHERE WORKDEPT = 'A00' ORDER BY SALARY
SALARY

39250.00
46500.00
49250.00
66500.00
152750.00
5 record(s) selected.