ruby on rails - What kind of migration is this? -

i trying setup model based on pre-built model has following code in migration:

   def change       create_table :friendships |t|          t.string :user_id, :friend_user_id          t.string :status        end   end 

i t.string :status part column being created use string. don't understand t.string :user_id, :friend_user_id part there 2 attributes on same line.

in first line, 2 columns being created named user_id , friend_user_id having string data type. in second line there column being created named status having string data type. in migrations can write column names in 1 line have same data type. i.e. migration can written this.

def change   create_table :friendships |t|     t.string :user_id, :friend_user_id, :status   end end