Type Property Example (Field) (VC++)

This example demonstrates the Type property by displaying the name of the constant that corresponds to the value of the Type property of all the Field objects in the Employees table. The FieldType function is required for this procedure to run.

// BeginTypeFieldCpp
#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 TypeX(void);
_bstr_t FieldType(int intType); 
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

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

    TypeX();

    ::CoUninitialize();
}

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

    // Define string variables.
    _bstr_t strCnn("Provider='sqloledb';Data Source='MySqlServer';"
        "Initial Catalog='pubs';Integrated Security='SSPI';");

    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr  pRstEmployees  = NULL;
    FieldsPtr  pFldLoop      = NULL;

    try
    {  
        // Open recordset with data from Employee table.
        TESTHR(pRstEmployees.CreateInstance(__uuidof(Recordset)));
        pRstEmployees->Open ("employee",strCnn,
            adOpenForwardOnly, adLockReadOnly, adCmdTable);

        printf("Fields in Employee Table:\n\n");

        // Enumerate the Fields collection of the Employees table.
        pFldLoop = pRstEmployees->GetFields();
        int intLine = 0;
        for (int intFields = 0; intFields < (int)pFldLoop->
            GetCount(); intFields++)
        {
            _variant_t Index;
            Index.vt = VT_I2;
            Index.iVal = intFields;
            printf("  Name: %s\n" ,
                (LPCSTR) pFldLoop->GetItem(Index)->GetName());
            printf("  Type: %s\n\n",
                (LPCTSTR)FieldType(pFldLoop->GetItem(Index)->Type));
            intLine++;
            if(intLine % 5 == 0)
            {
                printf("Press any key to continue...");
                getch();
                system("cls");
            }
        }
    }
    catch (_com_error &e)
    {
       // Notify the user of errors if any.
       // Pass a connection pointer accessed from the Recordset.
        _variant_t vtConnect = pRstEmployees->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 (pRstEmployees)
        if (pRstEmployees->State == adStateOpen)
            pRstEmployees->Close();
}

///////////////////////////////////////////////
//                                           //
//             FieldType Function            //
//                                           //
///////////////////////////////////////////////
_bstr_t FieldType(int intType) 
{
        _bstr_t strType; 
        switch(intType) 
        {
            case adChar:
                 strType = "adChar";
                break;
            case adVarChar:
                strType = "adVarChar";
                break;
            case adSmallInt:
                strType = "adSmallInt";
                break;
            case adUnsignedTinyInt:
                strType = "adUnsignedTinyInt";
                break;
            case adDBTimeStamp:
                strType = "adDBTimeStamp";
                break;
            default:
                break;
        }
        return strType;
}

///////////////////////////////////////////////
//                                           //
//    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("Error number: %x\t%s\n", pErr->Number, 
                (LPCSTR) 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);
}
// EndTypeFieldCpp

See Also

Field Object | Type Property