function showdata(selectobj)
{
	if ( selectobj.value != 0 )
		self.location.href='readings.php?id='+selectobj.value;
}

function showdaterange(selectobj)
{
	if (selectobj.value == 0 )
	{
		document.getElementById('fdate').disabled = true;
		document.getElementById('tdate').disabled = true;
	}
	else
	{
		document.getElementById('fdate').disabled = false;
		document.getElementById('tdate').disabled = false;
	}
}

function showButton(selectobj)
{
	if (selectobj.value == "")
		document.getElementById('chart').disabled = true;
	else
		document.getElementById('chart').disabled = false;
}