NumericScale and Precision Properties Example (VC++)

NumericScale and Precision Properties Example (VC++)

This example uses the NumericScale and Precision properties to display the numeric scale and precision of fields in the Discounts table of the Pubs database.

#import "C:\Program Files\Common Files\System\ADO\msado15.dll" \
    no_namespace rename("EOF", "EndOfFile")

#include <ole2.h>
#include <stdio.h>
#include <conio.h>

// Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void NumericScaleX(void);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

///////////////////////////////////////////////////////////
//                                                       //
//      Main Function                                    //
//                                                       //
///////////////////////////////////////////////////////////

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

    NumericScaleX();

    ::CoUninitialize();
}

///////////////////////////////////////////////////////////
//                                                       //
//      NumericScaleX Function                           //
//                                                       //
///////////////////////////////////////////////////////////

void NumericScaleX(void)
{
    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace
    _RecordsetPtr  pRstDiscounts  = NULL;
     FieldsPtr  fldTemp  = NULL;

    //Define Other Variables
    HRESULT  hr = S_OK;
    _variant_t Index;
    Index.vt = VT_I2;

    _bstr_t strCnn("Provider=sqloledb;Data Source=srv;"
         "Initial Catalog=Pubs;User Id=sa;Password=;");

    try
    {
        // Open recordset.
        TESTHR(pRstDiscounts.CreateInstance(__uuidof(Recordset)));
        pRstDiscounts->Open("Discounts", strCnn, adOpenForwardOnly,
            adLockReadOnly, adCmdTable);

        // Display numeric scale and precision of
        // numeric and small integer fields.
        fldTemp = pRstDiscounts->GetFields();

        for (int intLoop=0;intLoop < (int)fldTemp->GetCount();intLoop++)
        {
            Index.iVal = intLoop;

            if ((fldTemp->GetItem(Index)->Type == adNumeric) 
                || (fldTemp->GetItem(Index)->Type == adSmallInt))
            { 
                printf("Field: %s\n" ,(LPCSTR)fldTemp->
                    GetItem(Index)->GetName());
                printf("Numeric scale: %d\n", fldTemp->
                    GetItem(Index)->GetNumericScale());
                printf("Precision: %d\n", fldTemp->
                    GetItem(Index)->GetPrecision());
            }
        }
      // Clean up objects before exit. 
      pRstDiscounts->Close();
    }

    catch(_com_error &e)
    {    
       // Notify the user of errors if any.
       // Pass a connection pointer accessed from the Recordset.
        _variant_t vtConnect = pRstDiscounts->GetActiveConnection();

        // GetActiveConnection returns connect string if connection
        // is not open, else returns Connection object.
        switch(vtConnect.vt)
        {
            case VT_BSTR:
                PrintComError(e);
                break;
            case VT_DISPATCH:
                PrintProviderError(vtConnect);
                break;
            default:
                printf("Errors occured.");
                break;
        }
    }
}

///////////////////////////////////////////////////////////
//                                                       //
//      PrintProviderError Function                      //
//                                                       //
///////////////////////////////////////////////////////////

void PrintProviderError(_ConnectionPtr pConnection)
{
    // Print Provider Errors from Connection object.
    // pErr is a record object in the Connection's Error collection.
    ErrorPtr    pErr  = NULL;

    if( (pConnection->Errors->Count) > 0)
    {
        long nCount = pConnection->Errors->Count;

        // Collection ranges from 0 to nCount -1.
        for(long i = 0;i < nCount;i++)
        {
            pErr = pConnection->Errors->GetItem(i);
            printf("\t Error number: %x\t%s", pErr->Number,
                pErr->Description);
        }
    }
}

///////////////////////////////////////////////////////////
//                                                       //
//      PrintComError Function                           //
//                                                       //
///////////////////////////////////////////////////////////

void PrintComError(_com_error &e)
{
   _bstr_t bstrSource(e.Source());
   _bstr_t bstrDescription(e.Description());

    // Print COM errors. 
   printf("Error\n");
   printf("\tCode = %08lx\n", e.Error());
   printf("\tCode meaning = %s\n", e.ErrorMessage());
   printf("\tSource = %s\n", (LPCSTR) bstrSource);
   printf("\tDescription = %s\n", (LPCSTR) bstrDescription);
}