In mysql I have a `timestamp` with the field name `added_on`. I created that for a table of leads for a crm. But it's getting updated whenever I update a lead. I only want the timestamp to show only the added time. I dont want that to get updated everytime when I update or make changed in the lead.

Note: while creating the timestamp field i gave default value as timestamp and it shows `ON UPDATE CURRENT_TIMESTAMP` in the extras field after creating the field.

any ideas to stop the timestamp getting updated whenever I update the row?