MFC学习（一）——ADO数据库编程

这几篇是是在MFC框架下做保险项目的学习心得，只学了两周，但是还是学了很多知识。
下面介绍一下用ADO来进行数据库的各种操作。
1、数据库连接和打开
这次项目用的是SQL Server数据库，ADO连接数据遇到最重要的问题就是找到连接字符串，经过亲身经历各种尝试，在网上发现了一种无bug的方法，就是通过新建ado.udl文件，然后打开填写相应的数据库后用记事本打开即可得到连接字符串。下面是我封装的一个打开数据库的方法：

BOOL CDateOperator::OpenDateBase(){    if(NULL ==  m_pConnection){        AfxMessageBox(L"Create Instance failed!");        return FALSE;    }    if(m_pConnection){        try        {            const _bstr_t strSRC= "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=mydb;Data Source=LI5CH\\SQLEXPRESS";            HRESULT hr = m_pConnection->Open(strSRC,L"",L"",-1);        }        catch(_com_error &e)        {            CString errormsg;            errormsg.Format(L"关闭连接——操作错误！\r\n错误信息:%s",e.ErrorMessage());            AfxMessageBox(errormsg);        }    }    return TRUE;    }

2、ADO如何执行sql语句

BOOL CDateOperator::ExcuteSQL(CString strSQL){    if(NULL ==  m_pConnection) return FALSE;    try        {            HRESULT hr = m_pConnection->Execute(_bstr_t(strSQL),NULL,-1);        }        catch(_com_error &e)        {            return FALSE;        }        return TRUE;}

3、ADO如何插入记录

BOOL CDateOperator::Insert_db(DEMO objuser){    if(NULL == m_pConnection) return FALSE;    _RecordsetPtr m_pRecordset;    HRESULT hr = m_pRecordset.CreateInstance(L"ADODB.Recordset");    if(FAILED(hr)) return FALSE;    CString strSQL = L"SELECT User_ID, User_Name FROM fate";    hr = m_pRecordset->Open(_bstr_t(strSQL),m_pConnection.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdText);    if(FAILED(hr)){        m_pRecordset.Release();        return FALSE;    }    try    {        m_pRecordset->AddNew();    }    catch(_com_error &e)    {        m_pRecordset->Close();        m_pRecordset.Release();        return FALSE;    }//  byte byData[10000];    try    {        m_pRecordset->PutCollect("User_ID",_variant_t(objuser.User_ID));        m_pRecordset->PutCollect("User_Name",_variant_t(objuser.User_Name));    }    catch(_com_error &e)    {        m_pRecordset->Close();        m_pRecordset.Release();        return FALSE;    }    m_pRecordset->Update();    m_pRecordset->Close();    m_pRecordset.Release();    return TRUE; }

4、ADO如何查询数据

BOOL CDateOperator::Select_db(vector<DEMO>& vecObjUser){    if(NULL == m_pConnection) return FALSE;    _RecordsetPtr m_pRecordset;    HRESULT hr = m_pRecordset.CreateInstance(L"ADODB.Recordset");    if(FAILED(hr)) return FALSE;    vecObjUser.clear();    CString strSQL = L"SELECT User_ID, User_Name FROM fate";    hr = m_pRecordset->Open(_bstr_t(strSQL),m_pConnection.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdText);    if(FAILED(hr)){        m_pRecordset.Release();        return FALSE;    }    VARIANT_BOOL bRet = m_pRecordset->GetadoEOF();    while(!bRet){        _variant_t varUserID = m_pRecordset->GetCollect(L"User_ID");        _variant_t varUserName = m_pRecordset->GetCollect(L"User_Name");        DEMO objUser;        objUser.User_ID=varUserID.intVal;        _tcscpy(objUser.User_Name,(TCHAR*)(_bstr_t)varUserName);        vecObjUser.push_back(objUser);        m_pRecordset->MoveNext();        bRet = m_pRecordset->GetadoEOF();    }    m_pRecordset->Close();    m_pRecordset.Release();    return TRUE; }

5、ADO如何更新数据

BOOL CDateOperator::update_db(DEMO objuser){    if(NULL == m_pConnection) return FALSE;    _RecordsetPtr m_pRecordset;    HRESULT hr = m_pRecordset.CreateInstance(L"ADODB.Recordset");    if(FAILED(hr)) return FALSE;    CString strSQL;    strSQL.Format(L"SELECT User_ID, User_Name FROM fate WHERE User_ID=%d", objuser.User_ID);    hr = m_pRecordset->Open(_bstr_t(strSQL),m_pConnection.GetInterfacePtr(),adOpenStatic,adLockOptimistic,adCmdText);    if(FAILED(hr)){        m_pRecordset.Release();        return FALSE;    }//  byte byData[10000];    try    {        m_pRecordset->PutCollect("User_Name",_variant_t(objuser.User_Name));    }    catch(_com_error &e)    {        m_pRecordset->Close();        m_pRecordset.Release();        return FALSE;    }    m_pRecordset->Update();    m_pRecordset->Close();    m_pRecordset.Release();    return TRUE; }

6、下面贴一下构造和析构函数

CDateOperator::CDateOperator(void){    try    {        HRESULT hr =  m_pConnection.CreateInstance("ADODB.Connection");        if(FAILED(hr))        {            AfxMessageBox(L"Create Instance failed!");            m_pConnection = NULL;        }    }    catch(_com_error &e)    {    }}CDateOperator::~CDateOperator(void){    if(m_pConnection)    {        try        {            HRESULT hr =  m_pConnection->Close();        }        catch(_com_error &e)        {        }    }    m_pConnection.Release();    m_pConnection = NULL;}