comet is still very complicated to implement.
if you can build a static page everytime the db is updated, it will be far easier on your server. you can use simple HEAD requests to espablish when the data changed, saving the download of a file every second. heads usually bounce back in one packet.
you can run head every 5 seconds, and immed DL if the data changed.
BROWSER STATS [% share]
(2013/10/31) IE7:0.5, IE8:8.6, IE9:5.3, IE10:12.3, FF:17.7, CH:41.8, SF:8.1, MOBILE:20.4