title: Sharepoint calculated field's formula for created by
body: <p>i have a sharepoint list </p>
  
  <p>with 2 users for examole (user A and user B)</p>
  
  <p>i need a calculated field in the list items such that if user "A" created the    item the field vaule will be "X" and if user "B" created the item  fields value would be "Y"</p>
  
  <p>but i couldnt use [created by] in the furmiula of the calculated field !!  why is that ?!! and is there another way to do what i need to do ?!</p>