System.User default

Hi I have a authorisation form that I am doing, and a admin user fills the form out. But on my form theres a "completed by" column. The "completed by" column is populated to which ever admin user logs on to the system and fills the authorisation form out, which is perfect. But then the authorisation form must be approved by a Business Leader. So he/she logs on and they either approve it or declines the authorisation form. But the problem is that it changes my "completed by" column to the last person that loged on which is probably the business leader. Can someone please help me and tell me how to only populate the "completed by" column only once. Kind Regards, Michael
1 answers

Just add association from your object to the System.User object, and populate that association when someone completes the form (by using a custom save button)