ADO的参数化查询(关键字:ADO 参数化查询 , _ParameterPtr,
finix 2005-04-28 03:47:50 参数化有没有对查询语句的限制?
try
{
_CommandPtr cmd ;
cmd.CreateInstance(__uuidof(Command)) ;
cmd->Prepared = true;
CString sql2;
sql2.Format("select ? from tablename group by ?");
_ParameterPtr p1 =
cmd->CreateParameter(_bstr_t("field_name") ,
adBSTR , adParamInput ,
strlen("field_name") ,
"field_name") ;
cmd->Parameters->Append(p1) ;
_ParameterPtr p2 =
cmd->CreateParameter(_bstr_t("field_name") ,
adBSTR , adParamInput ,
strlen("field_name") ,
"field_name") ;
cmd->Parameters->Append(p2) ;
cmd->ActiveConnection = m_pConnection ;
cmd->CommandText = (LPCTSTR)sql2 ;
_variant_t vEmpty(DISP_E_PARAMNOTFOUND, VT_ERROR);
_RecordsetPtr set = cmd->Execute(NULL,&vEmpty,adCmdText) ;
运行出错
如果不加group by 子句,运行通过。 这是为什么?