optimizex.cpp

来自「visual c++ 很全的ado的sample」· C++ 代码 · 共 139 行

#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 OptimizeX(void);
void PrintProviderError(_ConnectionPtr pConnection);
void PrintComError(_com_error &e);

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

    OptimizeX();

    ::CoUninitialize();
}

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

    // Define string variables.
    _bstr_t strCnn("Provider=sqloledb;Data Source=srv;"
            "Initial Catalog=pubs;User Id=sa;Password=;");
    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr   pRst = NULL;

    try
    {
        TESTHR(pRst.CreateInstance(__uuidof(Recordset)));

        // Enable Index creation.
        pRst->CursorLocation = adUseClient;
        pRst->Open ("SELECT * FROM authors", strCnn,
            adOpenStatic, adLockReadOnly, adCmdText);

        // Create the index
        pRst->Fields->GetItem("zip")->Properties->
            GetItem("Optimize")->PutValue("True");

        // Find Akiko Yokomoto
        pRst->Find("zip = '94595'",1,adSearchForward);
        printf("\n%s %s    %s %s %s\n",
            (LPSTR) (_bstr_t) pRst->Fields->GetItem("au_fname")->Value,
            (LPSTR) (_bstr_t) pRst->Fields->GetItem("au_lname")->Value,
            (LPSTR) (_bstr_t) pRst->Fields->GetItem("address")->Value,
            (LPSTR) (_bstr_t) pRst->Fields->GetItem("city")->Value,
            (LPSTR) (_bstr_t) pRst->Fields->GetItem("state")->Value);

        // Delete the index
        pRst->Fields->GetItem("zip")->Properties->
            GetItem("Optimize")->PutValue("False");
        pRst->Close();
    }

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