How would you attack the statement below using UNION SELECT to get the right coupon. Please do not answer with ' or 1=1 #. Note: There are no filters.

PreparedStatement prepstmt = conn.prepareStatement("SELECT itemId, perCentOff, itemName FROM coupons JOIN items USING (itemId) WHERE couponCode = '" + couponCode + "';")

For full source code:

https://www.programcreek.com/java-api-examples/index.php?source_dir=SecurityShepherd-master/SecurityShepherdCore/src/servlets/module/challenge/SqlInjection5CouponCheck.java