VC++ 使用ADO操作数据库

>基础环境设置 

初始化com库 使用AfxOleInit()函数，可以在MFC环境中使用.

>定义一个connection对象,并登录sqlserver服务器

 Connection15Ptr pConnection;  
pConnection.CreateInstance("ADODB.Connection");

_bstr_t bstr_Connectionstring;
bstr_Connectionstring = SysAllocString(L"Provider=SQLOLEDB.1;Password=sa;Persist Security Info=True;User ID=sa;Initial Catalog=Northwind;Data Source=.");

pConnection->Open(bstr_Connectionstring,_bstr_t(""),_bstr_t(""),adConnectUnspecified );
pConnection->Close();
    

>定义一个RecordSet对象，并查询数据集

 Recordset15Ptr pRecordset; 
    pRecordset.CreateInstance("ADODB.Recordset");
    
    VARIANT vtRecord;
    vtRecord.vt = VT_I4;

    BSTR bstr_CommandText = SysAllocString(L"SELECT * FROM dbo.Employees");
    pRecordset  = pConnection->Execute(bstr_CommandText,&vtRecord,adCmdText );
    
    while(!pRecordset->AdoEOF)
    {
         OutputDebugString( (char*) ((_bstr_t) pRecordset->Fields->Item["FirstName"]->Value));
         OutputDebugString("\n");
        pRecordset->MoveNext();
       
    }
    pRecordset->Close();