Asp.net - Get A Windows Form Client To Update Everytime A Access Table On Webserver Changes?

I have a form with a list that shows information from a database. I want the list the update in run time (or almost real time) every time something changes in the database. These are the three ways I can think of to accomplish this:Set up a timer on the client to check every few seconds: I know how to do this now, but it would involve making and closing a new connection to the database hundreds of times an hour, regardless of whether there was any change Build something sort of like a TCP/IP chat server, and every time a program updates the database it would also send a message to the TCP/IP server, which in turn would send a message to the client's form: I have no idea how to do this right now Create a web service that returns the date and time of when the last time the table was changed, and the client would compare that time to the last time the client updated: I could figure out how to build a web service, but I don't how to do this without making a connection to the database anyway The second option doesn't seem like it would be very reliable, and the first seems like it would consume more resources than necessary. Is there some way to tell the client every time there is a change in the database without making a connection every few seconds, or is it not that big of a deal to make that many connections to a database?