MDAC 2.5 SDK - ADOX

NumericScale and Precision Properties Example (VC++)

This example demonstrates the NumericScale and Precision properties of the Column object. This code displays their value for the Order Details table of the Northwind database.

#import "c:\Program Files\Common Files\system\ado\msadox.dll" \
    no_namespace
#import "c:\Program Files\Common Files\system\ado\msado15.dll"

#include "iostream.h"
#include "stdio.h"
#include "conio.h"

//Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void NumericScalePrecX(void);

//////////////////////////////////////////////////////////
//                                                      //
//       Main Function                                  //
//                                                      //
//////////////////////////////////////////////////////////
void main()
{
    if(FAILED(::CoInitialize(NULL)))
        return;

    NumericScalePrecX();

    ::CoUninitialize();
}

//////////////////////////////////////////////////////////
//                                                      //
//          NumericScalePrecX Function                  //
//                                                      //
//////////////////////////////////////////////////////////
void NumericScalePrecX(void)
{
    HRESULT hr = S_OK;

    // Define ADOX object pointers.
    // Initialize pointers on define.
    // These are in the ADOX::  namespace.
    _CatalogPtr m_pCatalog = NULL;
    _TablePtr m_pTable = NULL;
    _ColumnPtr m_pColumn = NULL;

    //Define ADODB object pointers
    ADODB::_ConnectionPtr m_pCnn = NULL;

    //Declare string variables
    _bstr_t strCnn("Provider=Microsoft.Jet.OLEDB.4.0;"
        "Data Source=c:\\Program Files\\Microsoft Office\\"
        "Office\\Samples\\Northwind.mdb;");
    try
    {
        TESTHR(hr = m_pCnn.CreateInstance(__uuidof(ADODB::Connection)));

        TESTHR(hr = m_pCatalog.CreateInstance(__uuidof (Catalog)));

        // Connect the catalog.
        m_pCnn->Open (strCnn, "", "", NULL);

        m_pCatalog->PutActiveConnection(variant_t((IDispatch *)m_pCnn));
        
        // Retrieve the Order Details table
        m_pTable = m_pCatalog->Tables->GetItem("Order Details");

        // Display numeric scale and precision of
        // small integer fields.
        _variant_t vIndex;
        for (long lIndex=0; lIndex < m_pTable->Columns->Count; lIndex++)
        {
            vIndex = lIndex ;
            m_pColumn = m_pTable->Columns->GetItem(vIndex);
                if(m_pColumn->Type == adSmallInt)
                {
                    cout << "Column: " << m_pColumn->GetName() << endl;
                    cout << "Numeric scale: " << (_bstr_t) m_pColumn->
                        GetNumericScale() << endl;
                    cout << "Precision: " << m_pColumn->GetPrecision() << 
                        endl;
                }
        }
    }

    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        _bstr_t bstrSource(e.Source());
        _bstr_t bstrDescription(e.Description());

        printf("\n\tSource :  %s \n\tdescription : %s \n ",
             (LPCSTR)bstrSource,(LPCSTR)bstrDescription);
    }

    catch(...)
    {
        cout << "Error occured in include files...."<< endl;
    }
}