What is the easiest way to execute a query in Visual C ++

Question

I am using Visual C ++ 2005 and would like to know the simplest way to connect to MS SQL Server and execute a query.

I am looking for something as simple as the ADO.NET SqlCommand class, with it ExecuteNonQuery (), ExecuteScalar () and ExecuteReader ().

Sigh suggested an answer using CDatabase and ODBC.

Can anyone demonstrate how to do this using custom ATL templates for OleDb?

What about returning a scalar value from a query?

Answer 1

When using MFC CDatabase and ExecuteSQL if you are using an ODBC connection.

CDatabase db(ODBCConnectionString);
db.Open();
db.ExecuteSQL(blah);
db.Close();

Answer 2

OTL . :

#define OTL_ODBC_MSSQL_2008 // Compile OTL 4/ODBC, MS SQL 2008
//#define OTL_ODBC // Compile OTL 4/ODBC. Uncomment this when used with MS SQL 7.0/ 2000
#include <otlv4.h> // include the OTL 4.0 header file
#include <stdio>

int main()
{
  otl_connect db; // connect object
  otl_connect::otl_initialize(); // initialize ODBC environment
  try
  {
    int myint;

    db.rlogon("scott/tiger@mssql2008"); // connect to the database
    otl_stream select(10, "select someint from test_tab", db);

    while (!select.eof())
    {
      select >> myint;
      std::cout<<"myint = " << myint << std::endl;
    }
  }
  catch(otl_exception& p)
  {
    std::cerr << p.code << std::endl;     // print out error code
    std::cerr << p.sqlstate << std::endl; // print out error SQLSTATE
    std::cerr << p.msg << std::endl;      // print out error message
    std::cerr << p.stm_text << std::endl; // print out SQL that caused the error
    std::cerr << p.var_info << std::endl; // print out the variable that caused the error
  }

  db.logoff(); // disconnect from the database

  return 0;
}

OTL, IMO, , , ( ) .

Answer 3

:

#include <ole2.h>
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")
#include <oledb.h> 
void CMyDlg::OnBnClickedButton1()
{
    if ( FAILED(::CoInitialize(NULL)) )
        return;
    _RecordsetPtr pRs = NULL;

    //use your connection string here
    _bstr_t strCnn(_T("Provider=SQLNCLI;Server=.\\SQLExpress;AttachDBFilename=C:\\Program Files\\Microsoft SQL Server\\MSSQL.1\\MSSQL\\Data\\db\\db.mdf;Database=mydb;Trusted_Connection=Yes;MARS Connection=true"));
    _bstr_t a_Select(_T("select * from Table"));


    try {

            pRs.CreateInstance(__uuidof(Recordset));
            pRs->Open(a_Select.AllocSysString(), strCnn.AllocSysString(), adOpenStatic, adLockReadOnly, adCmdText);

            //obtain entire restult as comma separated text:
            CString text((LPCWSTR)pRs->GetString(adClipString, -1, _T(","), _T(""), _T("NULL")));

            //iterate thru recordset:
            long count = pRs->GetRecordCount();

            COleVariant var;
            CString strColumn1;
            CString column1(_T("column1_name")); 

            for(int i = 1; i <= count; i++)
            {
                var = pRs->GetFields()->GetItem(column1.AllocSysString())->GetValue();
                strColumn1 = (LPCTSTR)_bstr_t(var);
            }
    }
    catch(_com_error& e) {
            CString err((LPCTSTR)(e.Description()));
            MessageBox(err, _T("error"), MB_OK);
            _asm nop; //
    }
   // Clean up objects before exit.
   if (pRs)
       if (pRs->State == adStateOpen)
              pRs->Close();



     ::CoUninitialize();
}

Answer 4

Microsoft Enterprise Library. ++. SQlHelper , ADO. 2, .