Prevent people from adding item twice

[scootstah]

No, you'd need to get the values from the form using Javascript. It would look something like

var short, location, type;

short    = $('input[name="short"]').val();
location = $('input[name="location"]').val();
type     = $('input[name="type"]').val();

$.post("editcalendar.php",
{
	short    : short,
	location : location,
	type     : type		
},
function(data) {
	alert("Your event has been created, Close this window.");
}
);

 

Now do that for all of your form elements.