通过ADO访问SQLServer

#import "C:\Program Files\Common Files\System\ado\msado15.dll"\
 no_namespace rename("EOF", "EndOfFile")

 ...
 // 初始化数据库
 // 初始化OLE/COM库环境 ，为访问ADO接口做准备
 ::CoInitialize(NULL);

 _ConnectionPtr m_pConnection("ADODB.Connection");

 try
 {
  // 创建Connection对象
  m_pConnection.CreateInstance("ADODB.Connection");
  // 设置连接字符串，必须是BSTR型或者_bstr_t类型
  _bstr_t strConnect= "Provider=SQLOLEDB;Server=HostName\\SQLEXPRESS;Database=DBName;uid=sa;pwd=XXX;";
  //若数据库在网络上则Server为形如(192.168.1.5,3340)
  //用户sa和密码123只是针对我的库
  m_pConnection->Open(strConnect, "", "", adModeUnknown);
  if(m_pConnection==NULL)
   cerr << "ERROR: connection open error\n";
 }
 catch(_com_error e)
 { 
  // 显示错误信息
  cerr << "nERROR:" << (char*)e.Description();//抛出异常
  return -1;
 }

 // 可以把m_pRecordset作为全局，后面直接使用，获取_RecordsetPtr
 // 检查相关的表是否存在
 // 1.LogTalbe
 try
 {
  char* check_cmd("...");
  _RecordsetPtr r = m_pConnection->Execute(check_cmd,NULL,1);
 }
 catch(_com_error e)
 { 
  // 显示错误信息
  cerr << "ERROR:" << (char*)e.Description();
  return -1;
 }
 ...
 
 int id = (int)m_pRecordset->GetCollect("id");

 string name = string(_com_util::ConvertBSTRToString((_bstr_t)(r->GetCollect("name"))));

 // varbinary
 _variant_t v = rs->GetCollect("varbinary");
 pArray = v.Detach().parray;

 HRESULT hr = SafeArrayAccessData(pArray, (void HUGEP**)&token_info);
 if (FAILED(hr))
 {
  cout << "SafeArrayAccessData error: " << __FILE__ << " " << __LINE__ << endl;
  return -1;
 }
 size = pArray->rgsabound[0].cElements;

 if(g_pConnection->State) g_pConnection->Close();
 g_pConnection = NULL;
 ::CoUninitialize();