Question

I want to reduce polling in my application solution (many apps, 1 database, some 3rd party), customer wants an up-to-the-second GUI status of whats going on. Is it possible to add an event handler through .NET code to a table or database using SQL Server technologies?

Here are some solutions I’ve come across:

• SQL Server Service Broker with external activation – only launches new applications, not really an “event handler” kind of scenario
• CLR stored procedures – limited in functionality, obviously will have same issue getting event to the GUI status screen
• Go custom – I could do something crazy like having the SQL Server create a file (using XP command shell) in a folder with a trigger when a qualified event occurs, then have a FileSystemWatcher object pick up the file change event and trigger it that way, but that smells bad somehow.

Answer 1

You may want to look at SqlDependency. The only caveat is that, as the docs state,

SqlDependency was designed to be used in ASP.NET or middle-tier
services where there is a relatively small number of servers having
dependencies active against the database. It was not designed for use
in client applications, where hundreds or thousands of client
computers would have SqlDependency objects set up for a single
database server. If you are developing an application where you need
reliable sub-second notifications when data changes, review the
sections Planning an Efficient Query Notifications Strategy and
Alternatives to Query Notifications in the Planning for Notifications
topic in SQL Server Books Online.

In general though I find the above statement to be true for most SQL Server client applications, so hopefully this shouldn’t be a problem.