public class SubscriptionsWatcher
{
    private const string connectionString = "123";
 
    public void StartWatching()
    {
        SqlDependency.Stop(connectionString);
        SqlDependency.Start(connectionString);
        ExecuteWatchingQuery();
    }
 
    private void ExecuteWatchingQuery()
    {
        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();
            using (var command = new SqlCommand(
                "dbo.sp_GetChanges", connection))
            {
                var sqlDependency = new SqlDependency(command);
                sqlDependency.OnChange += new OnChangeEventHandler(OnDatabaseChange);
                command.ExecuteReader();
            }
        }
    }
 
    private void OnDatabaseChange(object sender, SqlNotificationEventArgs args)
    {
        SqlNotificationInfo info = args.Info;
        if (SqlNotificationInfo.Insert.Equals(info)
            || SqlNotificationInfo.Update.Equals(info)
            || SqlNotificationInfo.Delete.Equals(info))
        {
            //todo
        }
        ExecuteWatchingQuery();
    }
}