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Справочник по SQL Server Express LocalDB

Applies to:SQL Server

В этом разделе содержатся сведения о SQL Server Express LocalDB.

Code sample

В следующем образце демонстрируется использование API-интерфейса LocalDB. Перед запуском образца убедитесь в том, что база данных LocalDB установлена на компьютере. Вы можете установить LocalDB из программы установки в SQL Server Express.

// compile with: Advapi32.lib
#include <SDKDDKVer.h>
#include <stdio.h>

// To use LocalDB API, you must define LOCALDB_DEFINE_PROXY_FUNCTIONS before you include msoledbsql.h in one (and only one) of the
// source files in your program. LOCALDB_DEFINE_PROXY_FUNCTIONS causes code to be generated that binds to the LocalDB API at runtime.

#define LOCALDB_DEFINE_PROXY_FUNCTIONS
#include "msoledbsql.h"

HRESULT CreateAndStartLocalDBInstance(PWCHAR wszVersion, PWCHAR wszInstanceName) {
   HRESULT hr;

   if (SUCCEEDED(hr = LocalDBCreateInstance(wszVersion, wszInstanceName, 0)))
      hr = LocalDBStartInstance(wszInstanceName, 0, NULL, NULL);

   return hr;
}

HRESULT StopAndDeleteLocalDBInstance(PWCHAR wszInstanceName) {
   HRESULT hr;

   if (SUCCEEDED(hr = LocalDBStopInstance(wszInstanceName, 0, 30)))   // 30 seconds timeout
      hr = LocalDBDeleteInstance(wszInstanceName, 0);

   return hr;
}

void PrintLocalDBError(HRESULT hr) {
   HRESULT hrError;
   WCHAR wszMessage[1024];
   DWORD dwMessage = 1024;

   if (hr == LOCALDB_ERROR_NOT_INSTALLED)
      wprintf(L"Local DB is not installed.\n");

   else if (hr == LOCALDB_ERROR_CANNOT_LOAD_RESOURCES)
      wprintf(L"Cannot load resources for Local DB API DLL. Local DB installation is corrupted.\n");

   else if (FAILED(hrError = LocalDBFormatMessage(hr, 0, 0, wszMessage, &dwMessage)))
      wprintf(L"Cannot format an error message for a Local DB error code: %#x. LocalDBFormatMessage returned: %#x\n", hr, hrError);

   else
      wprintf(L"%s\n", wszMessage);
}

HRESULT PrintLocalDBInstances() {
   HRESULT hr;
   DWORD dwNumberOfInstances = 0;

   if (FAILED(hr = LocalDBGetInstances(NULL, &dwNumberOfInstances)))
      if (hr != LOCALDB_ERROR_INSUFFICIENT_BUFFER)
         return hr;

   PTLocalDBInstanceName localDBInstnces = (PTLocalDBInstanceName) malloc(dwNumberOfInstances * sizeof(TLocalDBInstanceName));
   if (localDBInstnces == NULL) {
      return HRESULT_FROM_WIN32(ERROR_OUTOFMEMORY);
   }

   if (FAILED(hr = LocalDBGetInstances(localDBInstnces, &dwNumberOfInstances))) {
      free(localDBInstnces);
      return hr;
   }

   for (DWORD i = 0; i < dwNumberOfInstances; i++) {
      LocalDBInstanceInfo localDBInstanceInfo;

      if (FAILED(hr = LocalDBGetInstanceInfo(localDBInstnces[i], &localDBInstanceInfo, sizeof(localDBInstanceInfo)))) {
         free(localDBInstnces);
         return hr;
      }

      wprintf(L"Name: %s State: %s Version: %u.%u.%u.%u\n",
         localDBInstnces[i],
         localDBInstanceInfo.bIsRunning ? L"running" : L"stopped",
         localDBInstanceInfo.dwMajor,
         localDBInstanceInfo.dwMinor,
         localDBInstanceInfo.dwBuild,
         localDBInstanceInfo.dwRevision);
   }

   free(localDBInstnces);
   return S_OK;
}

int main() {
   HRESULT hr;

   WCHAR wszInstanceName[] = L"Contoso";
   WCHAR wszVersion[] = L"11.0";

   if (FAILED(hr = CreateAndStartLocalDBInstance(wszVersion, wszInstanceName)))
      PrintLocalDBError(hr);

   PrintLocalDBInstances();

   if (FAILED(hr = StopAndDeleteLocalDBInstance(wszInstanceName)))
      PrintLocalDBError(hr);

   PrintLocalDBInstances();
}
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