$result = mysql_query("SELECT * FROM link");
$arr = array();
while ( $row = mysql_fetch_array($result) )
$arr[] = $row;

Array
(
    [0] => Array
      (
    	[0] => 2256
    	[link_id] => 2256
    	[1] => 748
    	[user_id] => 748
    	[2] => Вася
    	[note] => Вася
      )

    [1] => Array
      (
    	[0] => 2257
    	[link_id] => 2257
    	[1] => 749
    	[user_id] => 749
    	[2] => Петя
    	[note] => Петя
      )
)

Array
(
    [2256] => Array
      (
    	[1] => 748
    	[user_id] => 748
    	[2] => Вася
    	[note] => Вася
      )

    [2257] => Array
      (
    	[1] => 749
    	[user_id] => 749
    	[2] => Петя
    	[note] => Петя
      )
)