php and mysql security problem

Dear all I had a security problem with my homepage. I'm using the IIS 4 to host my webpage, and i got the php to run as the script of the webpage and the database i'm using for the database is mysql. Here is my question : There is a table in mysql which will let user to input some records to, then the user will update and retreive the records. But what i to do is limit the user update to the record which the user should be. I mean when user1 had insert a record into table, and he found out that there is some update need to do for the record he just inset, so he update that record. but i don't want other people can update his record. Is there also possible for php to grab the username and password from the window base which logged on to a Domain and pass it to MYSQL!! Thx Jack jack@nedcor.com