ADO訪問SQL（一）     
#import "C:Program FilesCommon FilesSystemadomsado15.dll"    no_namespace rename("EOF","rsEOF")
#include<iostream>

using namespace std;

//數(shù)據(jù)庫基本操作類
class DataAccess
{
private:
    //申明數(shù)據(jù)庫對(duì)象
    _ConnectionPtr pConn;
    _RecordsetPtr pRst;
    _CommandPtr pCmd;
    //連接標(biāo)識(shí)符
    bool flag;
public:
    DataAccess()
    {
        //初始化連接對(duì)象
        CoInitialize(NULL);
        //創(chuàng)建ADO連接實(shí)例
        pConn.CreateInstance(__uuidof(Connection));
        //創(chuàng)建ADO記錄集實(shí)例
        pRst.CreateInstance(__uuidof(Recordset));
        //創(chuàng)建ADO命令實(shí)例
        pCmd.CreateInstance(__uuidof(Command));
        //定義連接字符
        pConn->ConnectionString="Provider=SQLOLEDB;Server=(local);Database=Book; uid=sa; pwd=;";
        //標(biāo)識(shí)符默認(rèn)為false
        flag=false;
    }
    ~DataAccess()
    {
        //記錄集不為空，釋放記錄集
        if(pRst!=NULL)
        {
            pRst->Close();
            pRst.Release();
        }
        //Cmd類不為空，釋放Cmd
        if(pCmd!=NULL)
        {
            pCmd.Release();
        }
        //連接不為空，釋放連接
        if(pConn!=NULL)
        {
            pConn->Close();
            pConn.Release();
        }
    }
    //打開數(shù)據(jù)庫,成功返回TRUE,失敗返回FALSE
    BOOL openConn()
    {
        try
        {
            this->pConn->Open("","","",adConnectUnspecified);
            flag=true;
            return flag;
        }
        catch(_com_error &e)
        {
            return FALSE;
        }
    }
    //執(zhí)行SQL語句，成功返回_Recordset,失敗返回NULL
    _RecordsetPtr searchSql(_bstr_t sql)
    {
        try
        {
            if(flag==false)
            {
                this->openConn();
            }
            pCmd->put_ActiveConnection(_variant_t((IDispatch*)pConn));
            pCmd->CommandText=sql;
            this->pRst->Open(sql,(IDispatch*)this->pConn,adOpenDynamic,adLockOptimistic,adCmdText);
            //this->pRst=pCmd->Execute(NULL,NULL,adCmdText);
            return pRst;
        }
        catch(_com_error &e)
        {
            return NULL;
        }
    }
};