Hi Hibernate users!

today I am using Hibernate for my work and I have an un expected things and need your help!

When I update a record in a table, using my method names saveInfo(Tbluser, user) and the result is not expected! The fields I am not set value before call this method automatically set to NULL, although I wanna it must be the all value, like that

Table fields:

ID, UserName, Password, Email, RegisteredTime

and I change User's password only I call setId() and setPassword() only, the others fields set to NULL

Would you know how to keep them and solve this problem?
Thank you so much!