[Guid("694C1820-04B6-4988-928F-FD858B95C880")]public interface DBCOM_Interface{[DispId(1)]void Init(string userid , string password);[DispId(2)]bool ExecuteSelectCommand(string selCommand);[DispId(3)]bool NextRow();[DispId(4)]void ExecuteNonSelectCommand(string insCommand);[DispId(5)]string GetColumnData(int pos);}

[Guid("694C1820-04B6-4988-928F-FD858B95C880")]
publicinterfaceDBCOM_Interface
{
[DispId(1)]
voidInit(stringuserid , stringpassword);
[DispId(2)]
boolExecuteSelectCommand(stringselCommand);
[DispId(3)]
boolNextRow();
[DispId(4)]
voidExecuteNonSelectCommand(stringinsCommand);
[DispId(5)]
stringGetColumnData(intpos);
}

    // // Events interface Database_COMObjectEvents
[Guid("47C976E0-C208-4740-AC42-41212D3C34F0"), InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]public interface DBCOM_Events {}

[Guid("9E5E5FB2-219D-4ee7-AB27-E4DBED8E123E"),ClassInterface(ClassInterfaceType.None),ComSourceInterfaces(typeof(DBCOM_Events))]public class DBCOM_Class : DBCOM_Interface{

using System;
using System.Runtime.InteropServices;
using System.IO;
using System.Text;
using System.Data.SqlClient;
using System.Windows.Forms ;namespace Database_COMObject
{[Guid("694C1820-04B6-4988-928F-FD858B95C880")]public interface DBCOM_Interface{[DispId(1)]void Init(string userid , string password);[DispId(2)]bool ExecuteSelectCommand(string selCommand);[DispId(3)]bool NextRow();[DispId(4)]void ExecuteNonSelectCommand(string insCommand);[DispId(5)]string GetColumnData(int pos);}// Events interface Database_COMObjectEvents
[Guid("47C976E0-C208-4740-AC42-41212D3C34F0"), InterfaceType(ComInterfaceType.InterfaceIsIDispatch)]public interface DBCOM_Events {}[Guid("9E5E5FB2-219D-4ee7-AB27-E4DBED8E123E"),ClassInterface(ClassInterfaceType.None),ComSourceInterfaces(typeof(DBCOM_Events))]public class DBCOM_Class : DBCOM_Interface{private SqlConnection myConnection = null ; SqlDataReader myReader = null ;public DBCOM_Class(){}public void Init(string userid , string password){try{string myConnectString = "user id="+userid+";password="+password+";Database=NorthWind;Server=SKYWALKER;Connect Timeout=30";myConnection = new SqlConnection(myConnectString);myConnection.Open();//MessageBox.Show("CONNECTED");
}catch(Exception e){MessageBox.Show(e.Message);}}public bool ExecuteSelectCommand(string selCommand){if ( myReader != null ) myReader.Close() ;SqlCommand myCommand = new SqlCommand(selCommand);myCommand.Connection = myConnection;myCommand.ExecuteNonQuery();myReader = myCommand.ExecuteReader();return true ;}public bool NextRow(){if ( ! myReader.Read() ){myReader.Close();return false ;}return true ;}public string GetColumnData(int pos){Object obj = myReader.GetValue(pos);if ( obj == null ) return "" ;return obj.ToString() ;}public void ExecuteNonSelectCommand(string insCommand){SqlCommand myCommand = new SqlCommand(insCommand , myConnection);int retRows = myCommand.ExecuteNonQuery();}}
}

    CoInitialize(NULL);Database_COMObject::DBCOM_InterfacePtr p(__uuidof(Database_COMObject::DBCOM_Class));db_com_ptr = p ;db_com_ptr->Init("scott" , "tiger");

    char cmd[1024];sprintf(cmd , "SELECT COMPANYNAME , CONTACTNAME ,CONTACTTITLE , ADDRESS  FROM CUSTOMERS WHERE CUSTOMERID = '%s'" , m_id );const char *p ;bool ret = db_com_ptr->ExecuteSelectCommand(cmd);if ( ! db_com_ptr->NextRow() ) return ;_bstr_t mData = db_com_ptr->GetColumnData(3);p = mData ;m_address    =    (CString)p ;