_ConnectionPtr、_RecordsetPtr和_CommandPtr 打開和關閉

_ConnectionPtr：

_ConnectionPtr  m_pConnection;

HRESULT hr;

try{

hr = m_pConnection.CreateInstance(_uuidof(Connection));///建立Connection實例

if(SUCCEEDED(hr)){

   m_pConnection->ConnectionTimeout=600;//設置鏈接超時時間

   m_pConnection->CommandTimeout=120;//設置執行命令超時時間

hr = m_pConnection->Open("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=My.mdb","","",adModeUnknown);///鏈接數據庫

}

}

catch(_com_error e)///捕捉異常

{

CString errormessage;

errormessage.Format("鏈接數據庫失敗!\r\n錯誤信息:%s",e.ErrorMessage());

AfxMessageBox(errormessage);///顯示錯誤信息

return FALSE;

}

// 關閉ADO鏈接狀態

if (m_pConnection->GetState() == adStateOpen)

{

m_pConnection->Close();

}

if (m_pConnection)

{

m_pConnection.Release();

m_pConnection = NULL;

}

_RecordsetPtr:

_RecordsetPtr m_pRecordset;

m_pRecordset.CreateInstance("ADODB.Recordset");

m_pRecordset->Open(bstrSQL,_variant_t((IDispatch*)pConnection,true),adOpenStatic,adLockOptimistic,adCmdText);

if (m_pRecordset->GetState() == adStateOpen)

{

m_pRecordset->Close();

}

if (m_pRecordset)

{

m_pRecordset.Release();

m_pRecordset = NULL;

}

_CommandPtr：

_CommandPtr pCommandPtr;

try

{

hr = pCommandPtr.CreateInstance(_uuidof(Command));

if (SUCCEEDED(hr))

{

pCommandPtr->put_ActiveConnection(_variant_t((IDispatch*)pConnection,true));

pCommandPtr->CommandText=_bstr_t(strinSQL);

pCommandPtr->Execute(NULL,NULL,adCmdText);

}

}catch(_com_error *e)

{

return;

}

if (pCommandPtr)

{

pCommandPtr.Release();

pCommandPtr = NULL;

}