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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.

// BeginNumericScaleCpp.cpp
// compile with: /EHsc
#import "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 PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

int main() {
   if ( FAILED(::CoInitialize(NULL)) )
      return -1;

   NumericScaleX();
   ::CoUninitialize();
}

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

   // Define Other Variables
   _variant_t Index;
   Index.vt = VT_I2;

   _bstr_t strCnn("Provider='sqloledb'; Data Source='My_Data_Source'; Initial Catalog='pubs'; Integrated Security='SSPI';");

   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 (short 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());
         }
      }
   }
   catch(_com_error &e) {    
      // Display 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;
      }
   }

   // Clean up objects before exit.
   if (pRstDiscounts)
      if (pRstDiscounts->State == adStateOpen)
         pRstDiscounts->Close();
}

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);
      }
   }
}

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);
}
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