如何使用MFC进行数据库查询

如何使用MFC进行数据库查询

-----gwb2006(转载请保留)

最近因为工作需要，使用MFC访问远程数据库， 遇到一点小麻烦，不过幸好经过努力解决了。呵呵，一点小经验拿出来和大家分享下，希望后来者不会那么麻烦。

首先，MFC通过ODBC访问数据库，主要使用两个类，一个是CDataBase，一个是CRecordset。第一个是用于建立数据库连接的，第二个是数据集，用来查询的。步骤如下：

1.实例化一个CDataBase对象，并建立连接
CDataBase database;
database.OpenEx( _T( "DSN=odbclink" ),CDatabase::noOdbcDialog);//odbclink为数据源名称
//判断一下是否正确打开
if(!database.IsOpen())
{
_tprintf(_T"打开失败");
}

2.从CRecordset继承一个类


class myRecorderSet : public CRecordset




...{


public:


myRecorderSet(CDatabase* pDatabase = NULL,CString sSQlstatment = "DNS = test1",int nParam=2);




~myRecorderSet()...{};


void Move( long nrows, WORD wfetchtype );


void SetInputParam(CString sUserID);


DECLARE_DYNAMIC(myRecorderSet)




int m_retreturn_value;


CString m_UserID;


CString m_UserName;


CString m_SqlStatment;




public:


virtual CString GetDefaultConnect(); // Default connection string


virtual CString GetDefaultSQL(); // Default SQL for Recordset


virtual void DoFieldExchange(CFieldExchange* pFX); // RFX support




#ifdef _DEBUG


virtual void AssertValid() const;


virtual void Dump(CDumpContext& dc) const;


#endif


};


void AFXAPI RFX_Textout(CFieldExchange * pfx, LPCTSTR szname,


CString& value, int nmaxlength, int ncolumntype, short nscale);


IMPLEMENT_DYNAMIC(myRecorderSet,CRecordset)




myRecorderSet::myRecorderSet(CDatabase* pdb,CString Sqlstatment,int nParam):CRecordset(pdb)




...{


m_UserID="";


m_UserName="";


m_nDefaultType = snapshot;


m_SqlStatment = Sqlstatment;


m_nParams=nParam;


}




CString myRecorderSet::GetDefaultConnect()




...{


return _T(m_SqlStatment);


}




CString myRecorderSet::GetDefaultSQL()




...{


return _T("");


}




void myRecorderSet::DoFieldExchange(CFieldExchange* pFX)




...{


pFX->SetFieldType(CFieldExchange ::outputParam); //set the field type to outputParam for the return value


RFX_Int(pFX, _T("@RETURN_VALUE"), m_retreturn_value); //bind the return value to the variable


pFX->SetFieldType(CFieldExchange ::inputParam); //reset the field type to inputParam


RFX_Text(pFX, "@issd", m_UserID); //,255,SQL_CHAR,0);


pFX->SetFieldType(CFieldExchange ::outputParam);


RFX_Text(pFX, "@nsssame", m_UserName); //bind the @m_UserName to the m_UseraName




}






/**//////////////////////////////////////////////////////////////////////////////


// myRecorderSet diagnostics




#ifdef _DEBUG


void myRecorderSet::AssertValid() const




...{


CRecordset::AssertValid();


}




void myRecorderSet::Dump(CDumpContext& dc) const




...{


CRecordset::Dump(dc);


}


#endif




void myRecorderSet::Move(long nrows, WORD wfetchtype)




...{


if (m_nFields)


CRecordset ::Move(nrows, wfetchtype);


else


m_bBOF = m_bEOF = true;


}


void myRecorderSet::SetInputParam(CString sUserID)




...{


m_UserID= sUserID;


}



未完待续......................