Unicode Data and Server Code Pages

Importante:
Questa funzionalità verrà rimossa in una delle prossime versioni di Microsoft SQL Server. Non utilizzare questa funzionalità in un nuovo progetto di sviluppo e modificare appena possibile le applicazioni in cui questa funzionalità viene utilizzata. Use CLR Integration instead.

The Extended Stored Procedure API is enabled for Unicode data; however, it is not enabled for Unicode metadata. The #define Unicode directive does not have any effect on the Extended Stored Procedure API.

All metadata returned by, or provided to the Extended Stored Procedure API by your extended stored procedure application is assumed to be in the multibyte code page of the server. The default code page of an Extended Stored Procedure API server application is the ANSI code page of the computer on which the application is running, which can be obtained by calling srv_pfield with the field parameter set to SRV_SPROC_CODEPAGE.

If your Extended Stored Procedure API application is Unicode-enabled, you must convert your Unicode metadata column names, error messages, and so on, to multibyte data before passing this data to the Extended Stored Procedure API.

Example

The following extended stored procedure provides an example of the Unicode conversions discussed. Note that:

• Column data is passed as Unicode data to srv_describe because the column is described to be SRVNVARCHAR.

• Column name metadata is passed to srv_describe as multibyte data.
  The extended stored procedure calls srv_pfield with the field parameter set to SRV_SPROC_CODEPAGE to obtain the multibyte code page of Microsoft SQL Server.

• Error messages are passed to srv_sendmsg as multibyte data.

  __declspec(dllexport) RETCODE proc1 (SRV_PROC *srvproc)
  {
      #define MAX_COL_NAME_LEN 25
      #define MAX_COL_DATA_LEN 50
      #define MAX_ERR_MSG_LEN 250
      #define MAX_SERVER_ERROR 20000
      #define XP_ERROR_NUMBER MAX_SERVER_ERROR+1
  
      int retval;
      UINT serverCodePage;
      CHAR *szServerCodePage;
  
      WCHAR unicodeColumnName[MAX_COL_NAME_LEN];
      CHAR multibyteColumnName[MAX_COL_NAME_LEN];
  
      WCHAR unicodeColumnData[MAX_COL_DATA_LEN];
  
      WCHAR unicodeErrorMessage[MAX_ERR_MSG_LEN];
      CHAR  multibyteErrorMessage[MAX_ERR_MSG_LEN];
  
      lstrcpyW (unicodeColumnName, L"column1");
      lstrcpyW (unicodeColumnData, L"column1 data");
      lstrcpyW (unicodeErrorMessage, L"No Error!");
  
      // Obtain server code page.
      //
      szServerCodePage = srv_pfield (srvproc, SRV_SPROC_CODEPAGE, NULL);    
      if (NULL != szServerCodePage)
          serverCodePage = atol(szServerCodePage);
      else 
      {   // Problem situation exists.
          srv_senddone(srvproc, (SRV_DONE_ERROR | SRV_DONE_MORE), 0, 0);
          return 1;
      }
  
      // Convert column name for Unicode to multibyte using the 
      // server code page.
      //
      retval = WideCharToMultiByte(  
          serverCodePage,                 // code page
          0,                              // default
          unicodeColumnName,              // wide-character string
          -1,                             // string is null terminated
          multibyteColumnName,            // address of buffer for new
                                          //   string
          sizeof (multibyteColumnName),   // size of buffer
          NULL, NULL);
  
      if (0 == retval)
      {
          lstrcpyW (unicodeErrorMessage, L"Conversion to multibyte
          failed.");
          goto Error;
      }
  
      retval = srv_describe (srvproc, 1, multibyteColumnName,
      SRV_NULLTERM, 
        SRVNVARCHAR, MAX_COL_DATA_LEN*sizeof(WCHAR), // destination
          SRVNVARCHAR, lstrlenW(unicodeColumnData)*sizeof(WCHAR),
          unicodeColumnData); //source
      if (FAIL == retval)
      {
          lstrcpyW (unicodeErrorMessage, L"srv_describe failed.");
          goto Error;
      }
  
     retval = srv_sendrow(srvproc);
      if (FAIL == retval)
      {
          lstrcpyW (unicodeErrorMessage, L"srv_sendrow failed.");
          goto Error;
      }
  
      retval = srv_senddone (srvproc, SRV_DONE_MORE|SRV_DONE_COUNT, 0, 1);
      if (FAIL == retval)
      {
          lstrcpyW (unicodeErrorMessage, L"srv_senddone failed.");
          goto Error;
      }
  
      return 0;
  Error:
      // convert error message from Unicode to multibyte.
      retval = WideCharToMultiByte(  
          serverCodePage,                 // code page
          0,                              // default
          unicodeErrorMessage,            // wide-character string
          -1,                             // string is null terminated
          multibyteErrorMessage,          // address of buffer for new
                                          //   string
          sizeof (multibyteErrorMessage), // size of buffer
          NULL, NULL);
  
  srv_sendmsg(srvproc, SRV_MSG_ERROR, XP_ERROR_NUMBER, SRV_INFO, 1,
              NULL, 0, __LINE__, 
              multibyteErrorMessage,
              SRV_NULLTERM);
  
      srv_senddone(srvproc, (SRV_DONE_ERROR | SRV_DONE_MORE), 0, 0);
  
      return 1;
  }