Your NPE is comming from line 48 (shows as line 3 below).
rsmd is null because your query was an update, not an execute. So, as others have said, this comes down to a design issue, not a database issue.
You have to make your code behave differently based on whether it's an update or execute.
Also, you definitely want to remove the quotes from around "null" on your INSERT statement in order for SQL to understand it correctly. That's not what's causing the NullPointerException.