代码: CString strConn=_T("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Spring.mdb");
CString strSql=_T("");
strSql.Format("select * from User where UserName=%s",(LPCTSTR) m_UserName);
::CoInitialize(NULL);
_ConnectionPtr pConn=NULL;
_RecordsetPtr pRecordSet=NULL;
try
{
pConn.CreateInstance(__uuidof (Connection));
pConn->Open((_bstr_t)strConn,"","",adConnectUnspecified);
pConn->Close(); }
catch(_com_error& e)
{
AfxMessageBox("not right");
return ;
}
::CoUninitialize();
第一次用ado,不知道哪里出问题了,debug 的时候发现pConn在CreateInstance后仍然是0,导致总是抛出异常
到底是什么问题呢?
{
m_pAccessConnection.CreateInstance(__uuidof(Connection));
_bstr_t bstrConnectionString="driver={Microsoft Access Driver (*.mdb)};dbq=db.mdb;";
m_pAccessConnection->Open(bstrConnectionString,_bstr_t("管理员"),_bstr_t("aaa"),adConnectUnspecified);
}
catch ( _com_error &e )
{
_bstr_t bstrSource (e.Source());
_bstr_t bstrDescription (e.Description());
CString strError;
strError.Format("无法连接Access数据库。\r\n错误代码是:%08lx\r\n错误的原因是:%s\r\n错误源是:%s\r\n错误的描述是:%s\r\n", e.Error (), e.ErrorMessage (), (LPCTSTR) bstrSource, (LPCTSTR) bstrDescription);
MessageBox (strError, bstrDescription,MB_OK);
return false;
}
catch(CException &e)
{
e.ReportError();
e.Delete();
return false;
}
catch (...)
{
TRACE ( "*** 无法解决的错误 ***" );
return false;
}
return true;
HRESULT hr = pConn.CreateInstance(__uuidof(Connection));
if(FAILED(hr))
AfxMessageBox("Failed");
如果失败那是你的COM环境没初始化好
然后做
try
{
pConn->Open((_bstr_t)strConn,"","",adConnectUnspecified); }
catch(_com_error& e)
{
AfxMessageBox("not right");
return ;
}
_ConnectionPtr pConn=NULL;
_RecordsetPtr pRecordSet=NULL;好象是你自己把pConn给清空了,为什么?去掉该行即可
_ConnectionPtr pConn=NULL;
_RecordsetPtr pRecordSet=NULL;
HRESULT hr = pConn.CreateInstance(__uuidof(Connection));
if(FAILED(hr))
AfxMessageBox("Failed");
如果失败那是你的COM环境没初始化好
然后做
try
{
pConn->Open((_bstr_t)strConn,"","",adConnectUnspecified); }
catch(_com_error& e)
{
AfxMessageBox("not right");
return ;
}