ADO连接数据库时的数据类型问题。
下面的程序编译能通过,但是运行时有错误提示。感觉是数据类型的问题。
#include <windows.h>
#include "stdio.h"
#import "c:\program files\common files\system\ado\msado15.dll" no_namespace rename("EOF","adoEOF")
LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("HelloWin") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ;
wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = 0 ;
wndclass.cbWndExtra = 0 ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;
if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return 0 ;
}
hwnd = CreateWindow (szAppName, // window class name
TEXT ("The Hello Program"), // window caption
WS_OVERLAPPEDWINDOW, // window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
CW_USEDEFAULT, // initial x size
CW_USEDEFAULT, // initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL) ; // creation parameters
ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ;
while (GetMessage (&msg, NULL, 0, 0))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
PAINTSTRUCT p;
HDC hdc;
CoInitialize(NULL);
_ConnectionPtr pconn("ADODB.Connection");
_RecordsetPtr prst("ADODB.Recordset");
switch (message)
{
case WM_CREATE:
pconn->Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=zhenwu.mdb","","",adConnectUnspecified);
prst->Open("zhenwu",_variant_t((IDispatch*)pconn,true),adOpenStatic,adLockReadOnly,adCmdTable);
return 0 ;
case WM_PAINT:
hdc=BeginPaint(hwnd,&p);
TextOut(hdc,100,100,(char *)((_bstr_t)prst->GetFields()->GetItem("name")->GetValue()),7*sizeof(char));
EndPaint(hwnd,&p);
return 0 ;
case WM_DESTROY:
PostQuitMessage (0) ;
return 0 ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}