Posts aleatorios en el index

<div class="left"><?php include('left-bar.php');?></div><!--end left-->
<div class="center">
<div class="box-titles">Todas las portadas</div>
<!---//////////////////////////-->
<?php
// How many adjacent pages should be shown on each side?
	$adjacents = 5;
	
	$query = "select COUNT(*) as num from covers order by id  desc";
	$total_pages = mysql_fetch_array(mysql_query($query));
	$total_pages = $total_pages['num'];
	
	$limit = 6; 								//how many items to show per page
	$page = $_GET['page'];
	 
	if($page) 
		$start = ($page - 1) * $limit; 			//first item to display on this page
	else
		$start = 0;								//if no page var is given, set start to 0
 	/* Get data. */
	$sql = "select * from covers order by id  desc LIMIT $start, $limit";
	 
	$result = mysql_query($sql);
	
	/* Setup page vars for display. */
	if ($page == 0) $page = 1;					//if no page var is given, default to 1.
	$prev = $page - 1;							//previous page is page - 1
	$next = $page + 1;							//next page is page + 1
	$lastpage = ceil($total_pages/$limit);		//lastpage is = total pages / items per page, rounded up.
	$lpm1 = $lastpage - 1;						//last page minus 1
	
	$pagination = "";
	if($lastpage > 1)
	{	
		$pagination .= "<div class=\"pagination\">";
		//previous button
		if ($page > 1) 
			$pagination.= "<a href=\"todas_las_portadas-$prev.html\">« previous</a>";
		else
			$pagination.= "<span class=\"disabled\">« previous</span>";	
		
		//pages	
		if ($lastpage < 7 + ($adjacents * 2))	//not enough pages to bother breaking it up
		{	
			for ($counter = 1; $counter <= $lastpage; $counter++)
			{
				if ($counter == $page)
					$pagination.= "<span class=\"current\">$counter</span>";
				else
					$pagination.= "<a href=\"todas_las_portadas-$counter.html\">$counter</a>";					
			}
		}
		elseif($lastpage > 5 + ($adjacents * 2))	//enough pages to hide some
		{
			//close to beginning; only hide later pages
			if($page < 1 + ($adjacents * 2))		
			{
				for ($counter = 1; $counter < 4 + ($adjacents * 2); $counter++)
				{
					if ($counter == $page)
						$pagination.= "<span class=\"current\">$counter</span>";
					else
						$pagination.= "<a href=\"todas_las_portadas-$counter.html\">$counter</a>";					
				}
				$pagination.= "...";
				$pagination.= "<a href=\"todas_las_portadas-$lpm1.html\">$lpm1</a>";
				$pagination.= "<a href=\"todas_las_portadas-$lastpage.html\">$lastpage</a>";		
			}
			//in middle; hide some front and some back
			elseif($lastpage - ($adjacents * 2) > $page && $page > ($adjacents * 2))
			{
				$pagination.= "<a href=\"todas_las_portadas-1.html\">1</a>";
				$pagination.= "<a href=\"todas_las_portadas-2.html\">2</a>";
				$pagination.= "...";
				for ($counter = $page - $adjacents; $counter <= $page + $adjacents; $counter++)
				{
					if ($counter == $page)
						$pagination.= "<span class=\"current\">$counter</span>";
					else
						$pagination.= "<a href=\"todas_las_portadas-$counter.html\">$counter</a>";					
				}
				$pagination.= "...";
				$pagination.= "<a href=\"todas_las_portadas-$lpm1.html\">$lpm1</a>";
				$pagination.= "<a href=\"todas_las_portadas-$lastpage.html\">$lastpage</a>";		
			}
			//close to end; only hide early pages
			else
			{
				$pagination.= "<a href=\"todas_las_portadas-1.html\">1</a>";
				$pagination.= "<a href=\"todas_las_portadas-2.html\">2</a>";
				$pagination.= "...";
				for ($counter = $lastpage - (2 + ($adjacents * 2)); $counter <= $lastpage; $counter++)
				{
					if ($counter == $page)
						$pagination.= "<span class=\"current\">$counter</span>";
					else
						$pagination.= "<a href=\"todas_las_portadas-$counter.html\">$counter</a>";					
				}
			}
		}
		
		//next button
		if ($page < $counter - 1) 
			$pagination.= "<a href=\"todas_las_portadas-$next.html\">Siguiente »</a>";
		else
			$pagination.= "<span class=\"disabled\">Siguiente »</span>";
		$pagination.= "</div>\n";		
	}
	
	$q=mysql_query("select * from covers order by id desc limit $start,$limit");

	$numr=mysql_num_rows($q);
	if ($numr==0)
	{
	echo '<div class="msg"><span class="big">No se encontraron Portadas para esta busqueda.</span> <br/>Vuelve a intentarlo mas tarde.</div>';
	}
	while($row=mysql_fetch_assoc($q)){
$cname = $row['title'];
$clink = preg_replace("![^a-z0-9]+!i", "-", $cname);
$clink = strtolower($clink);
?>
<!--///////////-->
<div class="cover-box">
<div class="cover-title"><div class="t-bg"><a class="fbctitle" href="portada-<?php echo $row['id'];?>-<?php echo $clink;?>.html"><?php echo $row['title'];?></a></div><div class="t-socail"><div class="fb-like" data-href="http://<?php echo $settings['siteurl'];?>/portada-<?php echo $row['id'];?>-<?php echo $clink;?>.html" data-send="false" data-layout="button_count" data-width="100" data-show-faces="false"></div></div></div>
<div class="fbcover"><a href="portada-<?php echo $row['id'];?>-<?php echo $clink;?>.html"><img src="uploads/<?php echo $row['picture'];?>" width="580" height="215" alt="<?php echo $row['title'];?> Facebook Timeline Cover">
<div class="click">&nbsp;</div>
</a></div>
</div><!--end cover box-->
<!--///////////-->
<?php } ?>
<div class="small-ads"><?php echo $adrow['ad2'];?></div>
<div class="pagediv"><?php echo $pagination;?></div>

$sql = "select * from covers order by rand() LIMIT $start, $limit";

<?php
// Guardamos en una variable el numero de registros existentes
$conex = mysqli_connect(....);
$consulta = mysqli_fetch_array(mysqli_query($conex,"SELECT count(*) FROM tabla;"), MYSQLI_NUM);
$total = $consulta[0];

// Sacamos el numero aleatorio entre 0 y el total menos 1 (porque empieza en 0) menos 10 (porque cojeremos 10 registros)
$naleatorio = rand(0,$total-1-10);

// la consulta final queda en
$consulta = mysqli_fetch_array(mysqli_query($conex,"SELECT * FROM tabla LIMIT $naleatorio,10;"));
?>

<?php
// Guardamos en una variable el id máximo entre los registros de la tabla
$conex = mysqli_connect(....);
$consulta = mysqli_fetch_array(mysqli_query($conex,"SELECT MAX(id) FROM tabla;"), MYSQLI_NUM);
$ultimo = $consulta[0];

// Obtenemos los 10 números aleatorios entre 0 o 1 (depende de cómo empiecen nuestros id) y el máximo
$numeros = array();

for (int i=0; i<10; i++) {
    $numeros[] = rand(0, $ultimo);
}

$listaid = implode(',', $numeros);

// Y obtenemos los registros con la consulta final
$consulta = mysqli_fetch_array(mysqli_query($conex,"SELECT * FROM tabla WHERE id IN ($listaid)"));
?>