title: Insert Array into MYSQL field
body: <p>For a forum, i want to enable the users to send messages to each other to. 
  In order to do this, I made a table called Contacts, within this table I have 5 collumns: The user_id, a collumn for storing Friends, one for storing Family, one for storing Business and one for other contacts. These last four should all contain an array, which holds the user_id's of that type of contact. The reason I chose for this design is because I don't want to type an awful lot or limit the users on the amount of friends, like friend1, friend2 etc. </p>
  
  <p>My question is: Is this correct how I do it? If not, what should be improved?And what type of MYSQL field should Friends, Family, Business and Other be?</p>