C#

public static DataTable GetAsyncDataTable(String Query, CommandType sqlCommandType)
       {
           Abstract.AbstractSqlCommand mySqlCommand = new Concrete.ConcreteSqlCommand();

           mySqlCommand.GetAsyncDataTableBegin(Query, sqlCommandType);

           queryDuration = mySqlCommand.queryDuration;
           return mySqlCommand.MyTable;

       }

 public override IAsyncResult GetAsyncDataTableBegin(String Query, CommandType sqlCommandType)
        {
            return GetAsyncDataTableBegin(Query, null, sqlCommandType, null);
        }

public override IAsyncResult GetAsyncDataTableBegin(String Query, List<SqlParameter> sqlParameters, CommandType sqlCommandType, String ConnectionString)
        {
            DateTime nu = DateTime.Now;
            SqlCommand command = Get(Query, sqlParameters, sqlCommandType, ConnectionString);
           return command.BeginExecuteReader(GetAsyncDataTableEnd, command, CommandBehavior.CloseConnection);
        }

public override void GetAsyncDataTableEnd(IAsyncResult myResult)
        {
            SqlCommand command = null;
            SqlDataReader dr = null;
            DateTime nu = DateTime.Now;
            DataTable myTable = new DataTable();

            try
            {
                command = (SqlCommand)myResult.AsyncState;
                dr = command.EndExecuteReader(myResult);
                myTable.Load(dr);
                MyTable = myTable; //MyTable is a public override DataTable MyTable (property)
            }
            catch (Exception err)
            {
                String poef = err.ToString();
            }
            finally
            {
                if (null != dr)
                    dr.Close();
                command.Connection.Close();
                DateTime klaar = DateTime.Now;
                queryDuration = (klaar - nu).Duration();
                string Time = queryDuration.ToString();
            }
        }