Question

i would like my windows service (to be written in .NET) to recognize when new rows are added to a specific table, but instead of pulling the data from the sql-server i would like to use a server push model.

does somebody has a hint for me how to achieve this?
i am using sql server 2005.

tia

Answer 1

There’s also the ADO.NET SqlDependency mechanism if you’re using client side ADO.NET with C# or VB.NET

A SqlDependency object can be
associated with a SqlCommand in order
to detect when query results differ
from those originally retrieved. You
can also assign a delegate to the
OnChange event, which will fire when
the results change for an associated
command. You must associate the
SqlDependency with the command before
you execute the command. The
HasChanges property of the
SqlDependency can also be used to
determine if the query results have
changed since the data was first
retrieved.

You basically associate a SqlDependency with your SqlCommand, and provide an event handler that gets called when values that make up the result set of that SqlDependency change.

using(SqlCommand cmd = new SqlCommand(queryStatement, _conn))
{ 
   cmd.Notification = null;

   SqlDependency dependency = new SqlDependency(cmd);

   dependency.OnChange += 
       new OnChangeEventHandler(OnChange);

    ......
}

In the event handler, you can then do whathever you need to do.

void OnChange(object sender, SqlNotificationEventArgs e)
{
  SqlDependency dependency = sender as SqlDependency;

  (do whatever you need to do - e.g. reload the data)

}

Marc