จะทำยังไง ให้การ Random ไม่ให้เกิดข้อมูลซ้ำกัน ถ้าหากมีการ Query 2 ครั้ง

<?
$objConnect = mysql_connect("localhost","root","1234") or die("Error Connect to Database");
$objDB = mysql_select_db("db",$objConnect); 
$query = "SELECT user_code,user_name,user_lname FROM user ORDER BY RAND() LIMIT 0,1";
$result = mysql_query($query);
if(!$result){ echo mysql_error(); }

while($line = mysql_fetch_array($result))

 {
	 echo "<center>";
	 echo "<table width='400' border='0' cellspacing='1' cellpadding='0'>";
         echo "<tr>";
	 echo "<td height='22' width='100'><div align='left'>รางวัลชนะเลิศ</div></td>";
         echo "<td height='22' width='10'><div align='right'>$line[user_code]</div></td>";
	 echo "</tr>";
	 echo "</table>";
	 echo "<br>";
 }
$query1 = "SELECT user_code,user_name,user_lname FROM user ORDER BY RAND() LIMIT 6";
$result1 = mysql_query($query1);
if(!$result1){ echo mysql_error(); }
while($line1 = mysql_fetch_array($result1))
 {
	 echo "<center>";
	 echo "<table width='400' border='0' cellspacing='1' cellpadding='0'>";
         echo "<tr>";
	 echo "<td height='22' width='100'><div align='left'>รางวัลชมเชย</div></td>";
         echo "<td height='22' width='10'><div align='right'>$line1[user_code]</div></td>";
	 echo "</tr>";
	 echo "</table>";
	 echo "<br>";
 }
?>