/// <summary>
        /// Simplify the creation of a TurboDB command object by allowing
        /// a CommandType and Command Text to be provided
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  TurboDBCommand command = CreateCommand(conn, CommandType.Text, "Select * from Customers");
        /// </remarks>
        /// <param name="connection">A valid TurboDBConnection object</param>
        /// <param name="commandType">CommandType (TableDirect, Text)</param>
        /// <param name="commandText">CommandText</param>
        /// <returns>A valid TurboDBCommand object</returns>
        public static TurboDBCommand CreateCommand(TurboDBConnection connection, CommandType commandType, string commandText )
        {
            if( connection == null ) throw new ArgumentNullException( "connection" );

            if( commandType == CommandType.StoredProcedure ) throw new ArgumentException("Stored Procedures are not supported.");

            // If we receive parameter values, we need to figure out where they go
            if ((commandText == null) && (commandText.Length<= 0)) throw new ArgumentNullException( "Command Text" );

            // Create a TurboDBCommand
            TurboDBCommand cmd = new TurboDBCommand(commandText, connection );
            cmd.CommandType = CommandType.Text ;

            return cmd;
        }
        /// <summary>
        /// Create and prepare a TurboDBCommand, and call ExecuteReader with the appropriate CommandBehavior.
        /// </summary>
        /// <remarks>
        /// If we created and opened the connection, we want the connection to be closed when the DataReader is closed.
        /// 
        /// If the caller provided the connection, we want to leave it to them to manage.
        /// </remarks>
        /// <param name="connection">A valid TurboDBConnection, on which to execute this command</param>
        /// <param name="transaction">A valid TurboDBTransaction, or 'null'</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="commandParameters">An array of TurboDBParameters to be associated with the command or 'null' if no parameters are required</param>
        /// <param name="connectionOwnership">Indicates whether the connection parameter was provided by the caller, or created by TurboDBHelper</param>
        /// <returns>TurboDBDataReader containing the results of the command</returns>
        private static TurboDBDataReader ExecuteReader(TurboDBConnection connection, TurboDBTransaction transaction, CommandType commandType, string commandText, TurboDBParameter[] commandParameters, TurboDBConnectionOwnership connectionOwnership)
        {
            if( connection == null ) throw new ArgumentNullException( "connection" );

            bool mustCloseConnection = false;
            // Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();
            try
            {
                PrepareCommand(cmd, connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection );

                // Create a reader
                TurboDBDataReader dataReader;

                // Call ExecuteReader with the appropriate CommandBehavior
                if (connectionOwnership == TurboDBConnectionOwnership.External)
                {
                    dataReader = cmd.ExecuteReader();
                }
                else
                {
                    dataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                }

                // Detach the TurboDBParameters from the command object, so they can be used again.
                // HACK: There is a problem here, the output parameter values are fletched
                // when the reader is closed, so if the parameters are detached from the command
                // then the TurboDBReader can´t set its values.
                // When this happen, the parameters can´t be used again in other command.
                bool canClear = true;
                foreach(TurboDBParameter commandParameter in cmd.Parameters)
                {
                    if (commandParameter.Direction != ParameterDirection.Input)
                        canClear = false;
                }

                if (canClear)
                {
                    cmd.Parameters.Clear();
                }

                return dataReader;
            }
            catch
            {
                if( mustCloseConnection )
                    connection.Close();
                throw;
            }
        }
 /// <summary>
 /// This method is used to attach array of TurboDBParameters to a TurboDBCommand.
 /// 
 /// This method will assign a value of DbNull to any parameter with a direction of
 /// InputOutput and a value of null.  
 /// 
 /// This behavior will prevent default values from being used, but
 /// this will be the less common case than an intended pure output parameter (derived as InputOutput)
 /// where the user provided no input value.
 /// </summary>
 /// <param name="command">The command to which the parameters will be added</param>
 /// <param name="commandParameters">An array of TurboDBParameters to be added to command</param>
 private static void AttachParameters(TurboDBCommand command, TurboDBParameter[] commandParameters)
 {
     if( command == null ) throw new ArgumentNullException( "command" );
     if( commandParameters != null )
     {
         foreach (TurboDBParameter p in commandParameters)
         {
             if( p != null )
             {
                 // Check for derived output value with no value assigned
                 if ( ( p.Direction == ParameterDirection.InputOutput ||
                     p.Direction == ParameterDirection.Input ) &&
                     (p.Value == null))
                 {
                     p.Value = DBNull.Value;
                 }
                 command.Parameters.Add(p);
             }
         }
     }
 }
        /// <summary>
        /// Executes the respective command for each inserted, updated, or deleted row in the DataSet.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  UpdateDataset(conn, insertCommand, deleteCommand, updateCommand, dataSet, "Order");
        /// </remarks>
        /// <param name="insertCommand">A valid transact-SQL statement to insert new records into the data source</param>
        /// <param name="deleteCommand">A valid transact-SQL statement to delete records from the data source</param>
        /// <param name="updateCommand">A valid transact-SQL statement used to update records in the data source</param>
        /// <param name="dataSet">The DataSet used to update the data source</param>
        /// <param name="tableName">The DataTable used to update the data source.</param>
        public static void UpdateDataset(TurboDBCommand insertCommand, TurboDBCommand deleteCommand, TurboDBCommand updateCommand, DataSet dataSet, string tableName)
        {
            if( insertCommand == null ) throw new ArgumentNullException( "insertCommand" );
            if( deleteCommand == null ) throw new ArgumentNullException( "deleteCommand" );
            if( updateCommand == null ) throw new ArgumentNullException( "updateCommand" );
            if( tableName == null || tableName.Length == 0 ) throw new ArgumentNullException( "tableName" );

            // Create a TurboDBDataAdapter, and dispose of it after we are done
            TurboDBDataAdapter dataAdapter = new TurboDBDataAdapter();
            try
            {
                // Set the data adapter commands
                dataAdapter.UpdateCommand = updateCommand;
                dataAdapter.InsertCommand = insertCommand;
                dataAdapter.DeleteCommand = deleteCommand;

                // Update the dataset changes in the data source
                dataAdapter.Update (dataSet,tableName);

                // Commit all the changes made to the DataSet
                dataSet.AcceptChanges();
            }
            catch (TurboDBException E)
            {string strError=E.Message;}
            finally{dataAdapter.Dispose();}
        }
        /// <summary>
        /// Execute a TurboDBCommand (that returns a resultset) against the specified TurboDBTransaction
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  XmlReader r = ExecuteXmlReader(trans, CommandType.Text, "Select * from TableTransaction where ProdId=?", new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="transaction">A valid TurboDBTransaction</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command using "FOR XML AUTO"</param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        /// <returns>An XmlReader containing the resultset generated by the command</returns>
        public static string ExecuteXml(TurboDBTransaction transaction, CommandType commandType, string commandText, params TurboDBParameter[] commandParameters)
        {
            if( transaction == null ) throw new ArgumentNullException( "transaction" );
            if( transaction != null && transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );

            //			// Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();
            bool mustCloseConnection = false;
            PrepareCommand(cmd, (TurboDBConnection)transaction.Connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection);

            // Create the DataAdapter & DataSet
            TurboDBDataAdapter obj_Adapter =new TurboDBDataAdapter (cmd);
            DataSet ds=new DataSet();
            ds.Locale  =CultureInfo.InvariantCulture;
            obj_Adapter.Fill(ds);

            // Detach the TurboDBParameters from the command object, so they can be used again
            cmd.Parameters.Clear();
            string retval= ds.GetXml();
            ds.Clear();
            obj_Adapter.Dispose ();
            return retval;
        }
        /// <summary>
        /// Execute a TurboDBCommand (that returns a resultset) against the specified TurboDBConnection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        /// string  r = ExecuteXml(conn, CommandType.Text, "Select * from TableTransaction where ProdId=?", new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connection">A valid TurboDBConnection</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command using "FOR XML AUTO"</param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        /// <returns>An string containing the resultset generated by the command</returns>
        public static string ExecuteXml(TurboDBConnection connection, CommandType commandType, string commandText, params TurboDBParameter[] commandParameters)
        {
            if( connection == null ) throw new ArgumentNullException( "connection" );

            bool mustCloseConnection = false;
            // Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();
            try
            {
                PrepareCommand(cmd, connection, (TurboDBTransaction)null, commandType, commandText, commandParameters, out mustCloseConnection );

                // Create the DataAdapter & DataSet
                TurboDBDataAdapter obj_Adapter =new TurboDBDataAdapter (cmd);
                DataSet ds=new DataSet();
                ds.Locale  =CultureInfo.InvariantCulture;
                obj_Adapter.Fill(ds);

                // Detach the TurboDBParameters from the command object, so they can be used again
                cmd.Parameters.Clear();
                string retval= ds.GetXml();
                 ds.Clear();
                 obj_Adapter.Dispose ();
                return retval;

            }
            catch
            {
                if( mustCloseConnection )
                    connection.Close();
                throw;
            }
        }
        /// <summary>
        /// Execute a TurboDBCommand (that returns a 1x1 resultset) against the specified TurboDBTransaction
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int orderCount = (int)ExecuteScalar(trans, CommandType.Text, "Select count(Order) from TableTransaction where ProdId=?", new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="transaction">A valid TurboDBTransaction</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        /// <returns>An object containing the value in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(TurboDBTransaction transaction, CommandType commandType, string commandText, params TurboDBParameter[] commandParameters)
        {
            if( transaction == null ) throw new ArgumentNullException( "transaction" );
            if( transaction != null && transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );

            // Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();
            bool mustCloseConnection = false;
            PrepareCommand(cmd, (TurboDBConnection)transaction.Connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection);

            // Execute the command & return the results
            object retval = cmd.ExecuteScalar();

            // Detach the TurboDBParameters from the command object, so they can be used again
            cmd.Parameters.Clear();
            return retval;
        }
        /// <summary>
        /// Execute a TurboDBCommand (that returns a 1x1 resultset) against the specified TurboDBConnection 
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  int orderCount = (int)ExecuteScalar(conn, CommandType.Text, "Select count(Order) from TableTransaction where ProdId=?", new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connection">A valid TurboDBConnection</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        /// <returns>An object containing the value in the 1x1 resultset generated by the command</returns>
        public static object ExecuteScalar(TurboDBConnection connection, CommandType commandType, string commandText, params TurboDBParameter[] commandParameters)
        {
            if( connection == null ) throw new ArgumentNullException( "connection" );

            // Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();

            bool mustCloseConnection = false;
            PrepareCommand(cmd, connection, (TurboDBTransaction)null, commandType, commandText, commandParameters, out mustCloseConnection );

            // Execute the command & return the results
            object retval = cmd.ExecuteScalar();

            // Detach the TurboDBParameters from the command object, so they can be used again
            cmd.Parameters.Clear();

            if( mustCloseConnection )
                connection.Close();

            return retval;
        }
        /// <summary>
        /// Execute a TurboDBCommand (that returns a resultset) against the specified TurboDBTransaction
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  DataSet ds = ExecuteDataset(trans, CommandType.Text, "Select * from TableTransaction where ProdId=?", new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="transaction">A valid TurboDBTransaction</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        /// <returns>A dataset containing the resultset generated by the command</returns>
        public static DataSet ExecuteDataset(TurboDBTransaction transaction, CommandType commandType, string commandText, params TurboDBParameter[] commandParameters)
        {
            if( transaction == null ) throw new ArgumentNullException( "transaction" );
            if( transaction != null && transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );

            // Create a command and prepare it for execution
            TurboDBCommand cmd = new TurboDBCommand();
            bool mustCloseConnection = false;
            PrepareCommand(cmd, (TurboDBConnection)transaction.Connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection);

            // Create the DataAdapter & DataSet
            //using( TurboDBDataAdapter da = new TurboDBDataAdapter(cmd) )

            TurboDBDataAdapter da = new TurboDBDataAdapter(cmd);

            DataSet ds = new DataSet();
            ds.Locale  =CultureInfo.InvariantCulture;

            // Fill the DataSet using default values for DataTable names, etc
            da.Fill(ds);

            // Detach the TurboDBParameters from the command object, so they can be used again
            cmd.Parameters.Clear();

            // Return the dataset
            return ds;
        }
        /// <summary>
        /// This method opens (if necessary) and assigns a connection, transaction, command type and parameters 
        /// to the provided command
        /// </summary>
        /// <param name="command">The TurboDBCommand to be prepared</param>
        /// <param name="connection">A valid TurboDBConnection, on which to execute this command</param>
        /// <param name="transaction">A valid TurboDBTransaction, or 'null'</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="commandParameters">An array of TurboDBParameters to be associated with the command or 'null' if no parameters are required</param>
        /// <param name="mustCloseConnection"><c>true</c> if the connection was opened by the method, otherwose is false.</param>
        private static void PrepareCommand(TurboDBCommand command, TurboDBConnection connection, TurboDBTransaction transaction, CommandType commandType, string commandText, TurboDBParameter[] commandParameters, out bool mustCloseConnection )
        {
            if( command == null ) throw new ArgumentNullException( "command" );

            if(commandType == CommandType.StoredProcedure ) throw new ArgumentException("Stored Procedures are not supported.");

            // If the provided connection is not open, we will open it
            if (connection.State != ConnectionState.Open)
            {
                mustCloseConnection = true;
                connection.Open();
            }
            else
            {
                mustCloseConnection = false;
            }

            // Associate the connection with the command
            command.Connection = connection;

            // Set the command text (SQL statement)
            command.CommandText = commandText;

            // If we were provided a transaction, assign it
            if (transaction != null)
            {
                if( transaction.Connection == null ) throw new ArgumentException( "The transaction was rollbacked or commited, please provide an open transaction.", "transaction" );
                command.Transaction = transaction;
            }

            // Set the command type
            command.CommandType = commandType;

            // Attach the command parameters if they are provided
            if (commandParameters != null)
            {
                AttachParameters(command, commandParameters);
            }
            return;
        }
        /// <summary>
        /// Private helper method that execute a TurboDBCommand (that returns a resultset) against the specified TurboDBTransaction and TurboDBConnection
        /// using the provided parameters.
        /// </summary>
        /// <remarks>
        /// e.g.:  
        ///  FillDataset(conn, trans, CommandType.Text, "Select * from TableTransaction where ProdId=?", ds, new string[] {"orders"}, new TurboDBParameter("@prodid", 24));
        /// </remarks>
        /// <param name="connection">A valid TurboDBConnection</param>
        /// <param name="transaction">A valid TurboDBTransaction</param>
        /// <param name="commandType">The CommandType (TableDirect, Text)</param>
        /// <param name="commandText">The T-SQL command</param>
        /// <param name="dataSet">A dataset wich will contain the resultset generated by the command</param>
        /// <param name="tableNames">This array will be used to create table mappings allowing the DataTables to be referenced
        /// by a user defined name (probably the actual table name)
        /// </param>
        /// <param name="commandParameters">An array of TurboDBParamters used to execute the command</param>
        private static void FillDataset(TurboDBConnection connection, TurboDBTransaction transaction, CommandType commandType, 
			string commandText, DataSet dataSet, string[] tableNames,
			params TurboDBParameter[] commandParameters)
        {
            if( connection == null ) throw new ArgumentNullException( "connection" );
            if( dataSet == null ) throw new ArgumentNullException( "dataSet" );

            // Create a command and prepare it for execution
            TurboDBCommand command = new TurboDBCommand();
            bool mustCloseConnection = false;
            PrepareCommand(command, connection, transaction, commandType, commandText, commandParameters, out mustCloseConnection );

            // Create the DataAdapter & DataSet
            TurboDBDataAdapter dataAdapter = new TurboDBDataAdapter(command);

            try
            {
                // Add the table mappings specified by the user
                if (tableNames != null && tableNames.Length > 0)
                {
                    string tableName = "Table";
                    for (int index=0; index < tableNames.Length; index++)
                    {
                        if( tableNames[index] == null || tableNames[index].Length == 0 ) throw new ArgumentException( "The tableNames parameter must contain a list of tables, a value was provided as null or empty string.", "tableNames" );
                        dataAdapter.TableMappings.Add(tableName, tableNames[index]);
                        tableName += (index + 1).ToString();
                    }
                }

                // Fill the DataSet using default values for DataTable names, etc
                dataAdapter.Fill(dataSet);

                // Detach the TurboDBParameters from the command object, so they can be used again
                command.Parameters.Clear();

                if( mustCloseConnection )
                    connection.Close();
            }
            finally
            {
                dataAdapter.Dispose();
            }
        }