使用本机错误控制对象和集合 (SQL Server Compact Edition)

在 SQL Server 2005 Compact Edition (SQL Server Compact Edition) 中，通过使用 SQL Server Compact Edition 错误控制对象和集合，可以在 Microsoft Visual C++ for Devices 中直接访问 Replication、RemoteDataAccess 和 Engine 对象错误。

对于生成的每一个错误，SSCEErrors 集合都包含一个 SSCEError 对象。每一个 SSCEError 对象又都包含一个 SSCEParams 集合。在 SSCEParams 集合的 SSCEParam 对象中可以检索到错误的说明。与 SQL Server 不同，SQL Server Compact Edition 以集合（包含六个参数）的形式返回错误的详细信息。在生成错误消息时，将使用一系列嵌套的 FOR 循环来检索每一个 SSCEError 对象的 SSCEParams 集合中的每一个 SSCEParam 对象。

本机程序通过向项目引用添加 Ca_mergex20.h 和 Ca_mergex20.lib，以及通过使用 include 指令引用这些文件，来引用 SQL Server 错误对象和集合。有关详细信息，请参阅对本机错误对象进行编程 (SQL Server Compact Edition)。

示例

下面的示例说明如何使用 Visual C++ for Devices 来显示 Replication、RemoteDataAccess 和 Engine 对象错误：

// Error handling example
#include     "ca_mergex20.h"

void    ShowErrors(ISSCEErrors* pISSCEErrors)
{
HRESULT       hr;
LONG          cbBuf;
LONG          i;
LONG          lErrorCount;
LONG          lErrorIndex;
LONG          lParamCount;
LONG          lParamIndex;
VARIANT       var;
VARIANT       varParam;
WCHAR         wszBuff[4096];
WCHAR*        pwszBuffPos   = &wszBuff[0];
BSTR          bstr;
ISSCEError*   pISSCEError   = NULL;
ISSCEParams*  pISSCEParams  = NULL;
ISSCEParam*   pISSCEParam   = NULL;
BOOL          fSuccess      = FALSE;

// Initialize the variants.
VariantInit(&var);
VariantInit(&varParam);

// Get the count of errors.
if(FAILED(hr = pISSCEErrors->get_Count(&lErrorCount))) goto Exit;
if (lErrorCount <= 0)
    {
    MessageBox(NULL, L"No extended error information.",L"ShowErrors", MB_OK);
    fSuccess = TRUE;
    goto Exit;
    }

// Display errors, one at a time, in a single message box.
// If there are too many errors, they might not all display correctly.
// If so, we recommend that you perform logic based on the number of errors.
for (lErrorIndex = 0; lErrorIndex < lErrorCount; lErrorIndex++)
    {
    cbBuf = swprintf(pwszBuffPos, L"E R R O R  %d of %d\r\n",
        lErrorIndex+1, lErrorCount);
    pwszBuffPos += cbBuf;

    // Get the next error record.
    var.vt = VT_I4;
    var.lVal = lErrorIndex;
    if(FAILED(hr = pISSCEErrors->get_Item(var, &pISSCEError))) goto Exit;

    // Error description
    if (FAILED(hr = pISSCEError->get_Description(&bstr))) goto Exit;
    cbBuf = swprintf(pwszBuffPos, L"DESCRIPTION: '%s'\r\n", bstr);
    pwszBuffPos += cbBuf;
    SysFreeString(bstr);

    // Error number
    if (FAILED(hr = pISSCEError->get_Number(&i))) goto Exit;
    cbBuf = swprintf(pwszBuffPos, L"NUMBER: %8.8X\r\n", i);
    pwszBuffPos += cbBuf;

    // Native error
    if (FAILED(hr = pISSCEError->get_NativeError(&i))) goto Exit;
    cbBuf = swprintf(pwszBuffPos, L"NATIVE_ERROR: %d\r\n", i);
    pwszBuffPos += cbBuf;

    // Error source
    if (FAILED(hr = pISSCEError->get_Source(&bstr))) goto Exit;
    cbBuf = swprintf(pwszBuffPos, L"SOURCE: '%s'\r\n", bstr);
    pwszBuffPos += cbBuf;
    SysFreeString(bstr);

    // Retrieve the error parameters.
    if (FAILED(hr = pISSCEError->get_Params(&pISSCEParams))) goto Exit;

    // Get the number of error parameters.
    if (FAILED(hr = pISSCEParams->get_Count(&lParamCount))) goto Exit;

    // Display the value of each parameter.
    for (lParamIndex = 0; lParamIndex < lParamCount; lParamIndex++)
        {

        // Get the parameter object.
        var.vt = VT_I4;
        var.lVal = lParamIndex;
        if (FAILED(hr = pISSCEParams->get_Item(var, &pISSCEParam))) goto Exit;

        // Get and display the parameter value.
        if (FAILED(hr = pISSCEParam->get_Param(&varParam))) goto Exit;
        if (VT_I4 == varParam.vt || VT_UI4 == varParam.vt)
            {
            cbBuf = swprintf(pwszBuffPos, L"P%d: %d\r\n", lParamIndex,
                (LONG) varParam.lVal);
            }
        else if (VT_I2 == varParam.vt || VT_UI2 == varParam.vt)
            {
            cbBuf = swprintf(pwszBuffPos, L"P%d: %d\r\n", lParamIndex,
                (LONG) varParam.iVal);
            }
        else if (VT_BSTR == varParam.vt)
            {
            cbBuf = swprintf(pwszBuffPos, L"P%d: '%s'\r\n", lParamIndex, 
                varParam.bstrVal);
            }
        pwszBuffPos += cbBuf;

        // Clear the variant.
        VariantClear(&varParam);

        // Release the parameter object.
        pISSCEParam->Release();
        pISSCEParam = NULL;
        }
    cbBuf = swprintf(pwszBuffPos, L"\r\n");
    pwszBuffPos += cbBuf;

    }

// Display the error information.

MessageBox(NULL, wszBuff,L"Error", MB_OK);
fSuccess = TRUE;

Exit:
// Release the parameter object.
if (pISSCEParam)
    {
    pISSCEParam->Release();
    pISSCEParam = NULL;
    }

// Release the parameters object.
if (pISSCEParams)
    {
    pISSCEParams->Release();
    pISSCEParams = NULL;
    }

// Release the error object.
if (pISSCEError)
    {
    pISSCEError->Release();
    pISSCEError = NULL;
    }

// The Errors object is released in calling routine.
if (!fSuccess)
    {
    MessageBox(NULL, L"Error while processing errors!",L"ShowErrors", MB_OK);
    }
return;
}

请参阅

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