Term: PERCENTILE_CONT

Definition:
The Oracle PL/SQL function PERCENTILE_CONT is a built in inverse distribution analytic function which works on a continuous distribution model to get the median of a column value. It takes a numeric input which is assumed as a percentile rank and a grouping specification as input. The method of linear interpolation is as below.

Calculate Row Number (R) of each row within the group using percentile value
Get CEIL(C) and FLOOR(F) value for the row number
If (C=F=R) then value at R
Else, (C-R) * (Value at F) + (R-F) * (Value at C)

Example Syntax:

PERCENTILE_CONT() WITHIN GROUP (ORDER BY   NULLS ) 

OVER ();

Example Usage:

The SQL statement below lists the median salary which has a percentile of 0.5 within each department:

SQL> SELECT EMPNO, DEPTNO, SALARY , PERCENTILE_CONT(0.5)  

	WITHIN GROUP (ORDER_BY SALARY DESC)

	OVER (PARTITION BY DEPTNO) "Percentile_Cont"

	FROM EMPLOYEE