assumption here is that you want to base this on the users local time (if you want server time, then just use the [man]TIME[/man]
function to determine the time and make the query
the best thing to do here is have small js function that gets the local users time and submit it back to you
<script langauge="javascript">
function GetTime(){
var mytime = new Date();
document.form1.thetime.value=mytime;
form.submit();
}
</script>
<body onload="GetTime();">
<form name=form1 method=post action=newpage.php>
<input type=hdden name=thetime>
</form>
</body>
this gives you a current date/time stamp and you can take that apart to get the hours and minutes to do the query on the next page to show the user the db data for that timeframe