Before persist check for the value if exists in the DB; you can do that by writing a
NativeQuery. Something like this -
SELECT COUNT(*) FROM <TABLE-NAME> WHERE <CONDITION--ALL KEYS WHICH DISTINGUISH THE PARTICULAR RECORD SHOULD BE COMING IN HERE>'
and check for the count variable if it is more than 1 then there is a value already present in the DB.
Hope this helps
if you are looking to enforce unique constraints, mark the field as unique to solve this problem
thanks for the reply, i had done this with the help of validator Attribute associated with input field.
sorry for reporting late