You need to change:
if(resultSet.next()){
to
while(resultSet.next()){
resultSet.next() moves to the next row of data so you can then read it. It also returns true if there was a row or false if there wasn't.
Currently your code is just asking the resultset to get the first or or do nothing, whereas using the while will create a loop which will run until there are no more rows left. (or not run at all if there was none).