reverse MD5 ???

Hello, I have a system that uses certain id info. This info is stored in a session cookie in MD5 format. At certain parts of the code I need to update or insert to MySQL DB with that id info value in cleartext. Is this possible? If so, how to put this to a sql query? $sqlquery = "insert into x_table (team_id,number,) values ('$team_id','$number') $team_id is the MD5 formatted cookie value and I need to put it to the x_table column team_id in cleartext. Thanks a lot -Will