please excuse this thread is for / in connection with this thread

in a datatble, say for example table 3 columns
emp_id
emp_name
emp_class

here i don't want field emp_id to repeat for each row,
i mean i want to set empty value in the data table keeping only the first row entry
this check & update needs to be done for each emp_id.

i have done it by comparing each row with all the row and then setting the values to empty
very nasty & resource consuming & time consuming & harder to code

please some professional approach for this please.