Updating table from JSON/MYSQL with jQuery

You could do it like this

Your table generation:

<?php
// example for one col
while($array = mysql_fetchassoc($result))
{
    ?>
    <tr>
      <td id="col_name_<?=$array['row_id']?>"><?=$array['col_val']?></td>
    </tr>
    <?
}
?>

Your AJAX respond should look like this

<?php
while($array = mysql_fetchassoc($result))
{
    ?>
      $('#col_name_<?=$array['row_id']?>').html('<?=$array['col_val']?>');
    <?
}
?>

I think the key features are

• javascript setTimeout() to fetch data every 15sec.
• a kind of hash comparison between client & server data to see if there is a modification
• a php function that extract just the modifications to apply
• a javascript to update the appointments sent by JSON

Maybe you should use a calendar tool for rendering.
Fullcalendar is a pretty good open-source solution for that.

For the updates, I would approach this by presenting the data like:

appointment_id, timestamp_start, timestamp_end, ...

With that you can know if the appointment already exists or if it's a modification (update or delete)
You can also deduce the dates to display

Edit

Since your table is not that big and always day/hour based, this will be much simpler to manage:

Javascript setTimeout() to fetch data every 15sec,
Retrieve the entire table by JSON,
Load it by building up the HTML with jQuery like:

table = $('#table_container');
/* data -> appointments indexed by hours/days fetched by JSON
 * x -> days, y -> hours
 */
for (y=0; data[y].length; y++) {
  tr = $('<tr />');
  table.append(tr);
  for (x=0; data[y][x]; x++) {
    td = $('<td />');
    td.html(data[y][x]);
    tr.append(td);
  }
}

not tested but rough idea