C#_SqlDependency的使用详解

ALTER DATABASE DATABASE_NAME SET ENABLE_BROKER

static string connectionString = @"your connect string";
        static void Main(string[] args)
        {
            SqlDependency.Start(connectionString);
            getDataWithSqlDependency();
            Console.WriteLine("Waiting for data changes");
            Console.WriteLine("Press enter to quit");
            Console.ReadLine();
            SqlDependency.Stop(connectionString);
        }
        static DataTable getDataWithSqlDependency()
        {
            using (var connection = new SqlConnection(connectionString))
            using (var cmd = new SqlCommand("SELECT productname FROM dbo.product;", connection))
            {
                var dt = new DataTable();
                var dependency = new SqlDependency(cmd);
                dependency.OnChange += new OnChangeEventHandler(onDependencyChange);
                connection.Open();
                dt.Load(cmd.ExecuteReader(CommandBehavior.CloseConnection));
                return dt;
            }
        }
        static void onDependencyChange(object sender,SqlNotificationEventArgs e)
        {
            Console.WriteLine($"OnChange Event fired. SqlNotificationEventArgs: Info={e.Info}, Source={e.Source}, Type={e.Type}.");
            if ((e.Info != SqlNotificationInfo.Invalid)
                && (e.Type != SqlNotificationType.Subscribe))
            {
                var dt = getDataWithSqlDependency();
                Console.WriteLine($"Data changed. {dt.Rows.Count} rows returned.");
            }
            else
            {
                Console.WriteLine("SqlDependency not restarted");
            }
            Console.ReadLine();
        }

conn =ConfigurationManager.ConnectionStrings["default"].ToString();
                //Start和Stop方法
                SqlDependency.Start(conn);
                Update(conn);
 private static void Update(string conn)
        {
            using (
                   SqlConnection connection =
                       new SqlConnection(conn))
            {
                //此处 要注意 不能使用*  表名要加[dbo]  否则会出现一直调用执行 OnChange
                string sql = "select agent from [dbo].[info]";
                using (SqlCommand command = new SqlCommand(sql, connection))
                {
                    connection.Open();
                    command.CommandType=CommandType.Text;
                    dependency = new SqlDependency(command);
                    dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
                    //必须要执行一下command
                    command.ExecuteNonQuery();
                    Console.WriteLine(dependency.HasChanges);
                }
            }
        }
        //update insert delete都会进入
        private static void dependency_OnChange(object sender, SqlNotificationEventArgs e)
        {
            Console.WriteLine("onchange方法中："+dependency.HasChanges);
            Console.WriteLine("数据库数据发生变化"+DateTime.Now);
            //这里要再次调用
            Update(conn);
        }