filterx.cpp

来自「visual c++ 很全的ado的sample」· C++ 代码 · 共 267 行

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

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

// Function declarations
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};
void FilterX(void);
_RecordsetPtr FilterField(_RecordsetPtr rstTemp, _bstr_t strField, _bstr_t strFilter);
void FilterX2(void);
void PrintProviderError(_ConnectionPtr pCnn1);
void PrintComError(_com_error &e);

void main()
{
    HRESULT hr = S_OK;

    if(FAILED(::CoInitialize(NULL)))
        return;

    FilterX();

    //Wait here for user to see the output..
    printf("\nPress any key to Continue...");
    getch();

    //Clear the screen for the next display   
    system("cls");

    FilterX2();

    //Wait here for user to see the output..
    printf("\nPress any key to Exit...");
    getch();
    ::CoUninitialize();
}

///////////////////////////////////////////////////////////
//                                                       //
//      FilterX Function                                 //
//                                                       //
///////////////////////////////////////////////////////////

void  FilterX()
{
    // Define ADO object pointers.
    // Initialize pointers on define.
    // These are in the ADODB::  namespace.
    _RecordsetPtr rstPublishers = NULL;
    _RecordsetPtr rstPublishersCountry = NULL;

    //Define Other Variables
    HRESULT hr = S_OK;
    _bstr_t strCnn("Provider=sqloledb;Data Source=srv;"
            "Initial Catalog=pubs;User Id=sa;Password=;");
    int intPublisherCount = 0;
    long recCount = 0;
    _bstr_t strCountry; 
    _bstr_t strMessage;
    char *tempStr;
    CHAR sz_CountryName[50];
    bool boolFlag = TRUE;
    try 
    {
        // Open recordset with data from Publishers table.
        rstPublishers.CreateInstance(__uuidof(Recordset));
        rstPublishersCountry.CreateInstance(__uuidof(Recordset));

        rstPublishers->CursorType = adOpenStatic;

        TESTHR(   rstPublishers->Open("publishers",strCnn, 
             adOpenStatic , adLockReadOnly,adCmdTable));

        // Populate the Recordset.
        intPublisherCount = rstPublishers->RecordCount;

        // Get user input.
        printf("Enter a country to filter on:");
        gets(sz_CountryName);

        // Trim the string
        tempStr = strtok(sz_CountryName, "  \t");
        strCountry = tempStr;
        if (tempStr == NULL)
        {
            boolFlag = FALSE;
        }

        if (boolFlag)
        {
            if (strcmp(sz_CountryName,""))
            {
                // Open a filtered Recordset object.
                rstPublishersCountry = FilterField(rstPublishers, 
                    "Country", strCountry);
                recCount = rstPublishersCountry->GetRecordCount();
                if (recCount==0)
                {
                    printf("\nNo publishers from that country.\n");
                }
                else
                {
                    // Print number of records for the original
                    // Recordset object and the filtered Recordset
                    // object.
                    printf("\nOrders in original recordset:\n%d",
                        intPublisherCount);
                    printf("\nOrders in filtered recordset "
                        "(Country = '%s'): \n%d\n\n", (LPCSTR)strCountry ,
                        rstPublishersCountry->RecordCount);
                }
                rstPublishersCountry->Close();
            }
        }
    }

    catch(_com_error &e)
    {
        // Notify the user of errors if any.
        _variant_t vtConnect = rstPublishers->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;
        }
    }
}

_RecordsetPtr FilterField(_RecordsetPtr rstTemp,_bstr_t strField,
    _bstr_t strFilter) 
{
        // Set a filter on the specified Recordset object and then
        // open a new Recordset object.
        rstTemp->Filter  = strField + " = '" + strFilter + "'";
        return rstTemp;
}

void FilterX2(void)
{
    _RecordsetPtr rstPublishers;
    CPublishers publishers;

    //Define Other Variables
    HRESULT hr = S_OK;
    IADORecordBinding   *picRs = NULL;  //Interface Pointer declared...

    _bstr_t strCnn("Provider=sqloledb;Data Source=srv;"
            "Initial Catalog=pubs;User Id=sa;Password=;");
    try
    {
        // Open recordset with data from Publishers table.
        rstPublishers.CreateInstance(__uuidof(Recordset)); 

        rstPublishers->CursorType = adOpenStatic;

        TESTHR(rstPublishers->Open("SELECT * FROM publishers WHERE "
            "Country='USA'",strCnn,adOpenStatic,adLockReadOnly,
            adCmdText));

        //Open an IADORecordBinding interface pointer 
        //which we'll use for Binding Recordset to a class
        TESTHR(rstPublishers->QueryInterface(
            __uuidof(IADORecordBinding), (LPVOID*)&picRs));

        //Bind the Recordset to a C++ Class here 
        TESTHR(picRs->BindToRecordset(&publishers));

        // Print current data in recordset.
        rstPublishers->MoveFirst();

        while (!rstPublishers->EndOfFile)
        {
            printf("%s, %s\n", 
                publishers.lP_pubnameStatus == adFldOK ? 
                publishers.m_szP_pubname: "<NULL>",
                publishers.lP_countryStatus == adFldOK ? 
                publishers.m_szP_country: "<NULL>");

            rstPublishers->MoveNext();
        }
        //Release the IADORecordset Interface.
        if (picRs)
            picRs->Release();

        // Clean up object before exit.
        rstPublishers->Close();
    }

    catch (_com_error &e)
    {
        // Notify the user of errors if any.
        _variant_t vtConnect = rstPublishers->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 pCnn1)
{
    // Print Provider Errors from Connection object.
    // pErr is a record object in the Connection's Error collection.
    ErrorPtr  pErr  = NULL;

    if( (pCnn1->Errors->Count) > 0)
    {
        long nCount = pCnn1->Errors->Count;
        // Collection ranges from 0 to nCount -1.
        for(long i = 0; i < nCount; i++)
        {
            pErr = pCnn1->Errors->GetItem(i);
            printf("\t Error number: %x\t%s", 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);
}