数据库查询问题

[jvy]

//为何查不到所要的信息
//info.mdb是一个已定义好的数据库,且其中表名为info
CDaoRecordset Recordset;
Recordset.m_pDatabase =&db;
CDaoTableDef DataTable(&db);
//这样为何不行
/*CDaoTableDef DataTable;
DataTable.m_pDatabase =&db*/

try
{
db.Open("info.mdb",FALSE,FALSE,_T(""));
}
catch(CDaoException *pe)
{
AfxMessageBox(pe->m_pErrorInfo ->m_strDescription );
}

if(db.IsOpen ())
{

try
{
DataTable.Open("info");
}
catch(CDaoException *pe)
{
AfxMessageBox(pe->m_pErrorInfo ->m_strDescription );
pe->Delete ();
}

try
{
Recordset.Open(&DataTable,dbOpenDynaset,dbAppendOnly|dbInconsistent);
}
catch(CDaoException *pe)
{
AfxMessageBox(pe->m_pErrorInfo ->m_strDescription );
pe->Delete ();
}

//这样不对?
CString str="用户名=\'";
str+="jvy\'";
if(Recordset.FindFirst (str))
AfxMessageBox(str);//判断是否查到

//如是这样的话,加入新记录的同时能查找的着
CString name;
Record.AddNew();
name="jvy";
temp=COleVariant(name,VT_BSTRT);
Record.SetFieldValue("用户名",temp);
Record.Update();
if(Record.FindFirst("用户名='jvy'"))AfxMessageBox("find!");