Have one column with in Database table with datatype as
TimeStamp and while selecting the row we will read the
TimeStamp value, which we can compare at the time of updation, 

if both values are same then we can update that row
otherwise we can resist the user from updating saying that
someone has updated the row, you can't update it.

You can use one primary key and one timestamp field to sort
out the problem of concurrency. 
The steps are like this
1.Fetch the record from database and store the primary key
value and timestamp in the session.
2.Update the same record with new values other fields using
the same session values for primary key and timestamp fields.

we can have to use exclusive locks on the table thats why 
we can't change data at a time..