[FIXED] 'ADD_MONTHS' is not recognized as a function or procedure in Derby Database

Issue

I created table using Derby database

CREATE TABLE PROJECT
(PID  INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
PSDATE DATE,
PDURATION INTEGER,
PEDATE DATE,
PRIMARY KEY (PID)
);

I attempted to update end date in this project table, adding duration to start date

UPDATE PROJECT
SET PEDATE = ADD_MONTHS (PROJECT.PSDATE, PROJECT.PDURATION)
WHERE PID = PROJECT.PID;

But I am getting below error

"[Exception, Error code 30,000, SQLState 42Y03] 'ADD_MONTHS' is not recognized as a function or 
 procedure.
 Line 1, column 1"

Thanks in advance to help me to solve this problem

Solution

As a update Query this works in Derby.

  UPDATE PROJECT 
  SET PEDATE = DATE( {fn TIMESTAMPADD(SQL_TSI_MONTH, PDURATION, PSDATE)} );

Answered By - tharinduhd
Answer Checked By - Pedro (JavaFixing Volunteer)