js update-nutie databázy každú sekundu

<?php
include "connect.php";
?>
<script>
var lama=0;
function pridaj(){
<?php
$a=mysql_query("select * from tabulka");                                     
$b=mysql_fetch_array( $a);
$cislo=$b["cislo"];
mysql_query("update tabulka set cislo='$cislo'+'50'");
?>
}
function ukaz(){
document.getElementById("tu").innerHTML=<?php echo $cislo; ?>;
}
setInterval("pridaj()", 1000);
setInterval("ukaz()", 1000);
</script>
<div id=tu></div>