public static void T_InsertAndSelect_Async()
        {


            System.Diagnostics.Stopwatch stopW = new System.Diagnostics.Stopwatch();
            stopW.Start();
            var connStr = GetMySqlConnString();
            var conn = new MySqlConnection(connStr);
            conn.UseConnectionPool = true;

            var tc = new TaskChain();
            conn.AsyncOpen(tc);

            {
                //drop table if exist
                string sql = "drop table if exists test001";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }


            {
                string sql = "create table test001(col_id  int(10) unsigned not null auto_increment, col1 int(10)," +
                   "col2 char(2),col3 varchar(255),col4 datetime, primary key(col_id) )";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }

            for (int i = 0; i < 2000; ++i)
            {

                string sql = "insert into test001(col1,col2,col3,col4) values(10,'AA','123456789','0001-01-01')";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);

            }

            conn.AsyncClose(tc);
            tc.WhenFinish(() =>
            {

                stopW.Stop();
                Report.WriteLine("avg:" + stopW.ElapsedTicks);
            });
            tc.Start();


        }
        public static void T_InsertAndSelect_Async3()
        {
            System.Diagnostics.Stopwatch stopW = new System.Diagnostics.Stopwatch();
            stopW.Start();
            var connStr = GetMySqlConnString();
            var conn = new MySqlConnection(connStr);
            conn.UseConnectionPool = true;

            var tc = new TaskChain();
            //add task chain too connection object 
            conn.AsyncOpen(tc);
            //-----------------------------------------
            {
                //drop table if exist
                string sql = "drop table if exists test001";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }
            //----------------------------------------- 
            {
                //drop table if exist
                string sql = "drop table if exists test001";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }
            //----------------------------------------- 
            {
                string sql = "create table test001(col_id  int(10) unsigned not null auto_increment, col1 int(10)," +
                   "col2 char(2),col3 varchar(255),col4 datetime, primary key(col_id) )";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }
            //-----------------------------------------
            for (int i = 0; i < 100; ++i)
            {
                string sql = "insert into test001(col1,col2,col3,col4) values(10,'AA','123456789','0001-01-01')";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteNonQuery(tc);
            }
            //-----------------------------------------
            {
                string sql = "select * from test001";
                var cmd = new MySqlCommand(sql, conn);

                cmd.AsyncExecuteSubTableReader(tc, subtable =>
                {
                    //when new task is add after tc is started
                    //then this new task is immmediately insert 
                    //after current task
                   
                });
            }
            {
                string sql = "select sysdate()";
                var cmd = new MySqlCommand(sql, conn);
                cmd.AsyncExecuteScalar(tc, obj =>
                {

                });
            }
            //-----------------------------------------
            conn.AsyncClose(tc);
            tc.WhenFinish(() =>
            {
                stopW.Stop();
                Report.WriteLine("avg:" + stopW.ElapsedTicks);
            });
            tc.BeforeEachTaskBegin(() =>
            {
                Console.WriteLine(tc.CurrentTaskIndex + "/" + tc.TaskCount);
            });
            //----------------------------------------
            tc.Start();
        }
        public static void T_Select_sysdate3()
        {
            //prefer this

            var connStr = GetMySqlConnString();
            var conn = new MySqlConnection(connStr);
            var tc = new TaskChain();
            conn.AsyncOpen(tc);
            var cmd = new MySqlCommand("select sysdate()", conn);
            cmd.AsyncExecuteSubTableReader(tc, reader =>
            {
                if (reader.Read())
                {
                    var dtm = reader.GetDateTime(0);
                }
            });
            conn.AsyncClose(tc);
            tc.WhenFinish(() =>
            {

            });
            tc.Start();
        }
        public static void T_InsertAndSelect()
        {

            try
            {
                var tc = new TaskChain();

                var connStr = GetMySqlConnString();
                var conn = new MySqlConnection(connStr);
                conn.UseConnectionPool = true;
                conn.AsyncOpen(tc);

                DropTableIfExists(conn, tc);
                CreateTable(conn, tc);
                for (int i = 0; i < 1; ++i)
                {
                    InsertData(conn, tc);
                }
                SelectDataBack(conn, tc);

                conn.AsyncClose(tc);
                //
                tc.WhenFinish(() =>
                {

                });
                tc.BeforeEachTaskBegin(() =>
                {

                });
                tc.Start();

            }
            catch (Exception ex)
            {

            }
        }