title: 'ADD_MONTHS' is not recognized as a function or procedure in Derby Database
body: <p>I created table using Derby database</p>
  <pre><code>CREATE TABLE PROJECT
  (PID  INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY,
  PSDATE DATE,
  PDURATION INTEGER,
  PEDATE DATE,
  PRIMARY KEY (PID)
  );
  </code></pre>
  <p>I attempted to update end date in this project table, adding duration to start date</p>
  <pre><code>UPDATE PROJECT
  SET PEDATE = ADD_MONTHS (PROJECT.PSDATE, PROJECT.PDURATION)
  WHERE PID = PROJECT.PID;
  </code></pre>
  <p>But I am getting  below error</p>
  <pre><code>&quot;[Exception, Error code 30,000, SQLState 42Y03] 'ADD_MONTHS' is not recognized as a function or 
   procedure.
   Line 1, column 1&quot;
  </code></pre>
  <p>Thanks in advance to help me to solve this problem</p>
  <p><a href="https://i.stack.imgur.com/qahNC.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qahNC.jpg" alt="Image1" /></a></p>