Coluna de exibição do SQL Server Native Client e metadados de catálogo para colunas esparsas (OLE DB)

Aplica-se a: SQL Server Banco de Dados SQL do Azure Instância Gerenciada de SQL do Azure PDW (Sistema de Plataforma de Análise) do Azure Synapse Analytics

Este exemplo compila uma tabela com três colunas: uma coluna esparsa, uma coluna que não é esparsa e uma coluna de conjunto de colunas. Em seguida, o exemplo exibe o sinalizador OLE DB mostrando os metadados da coluna e do catálogo paras as colunas que não são esparsas e para a coluna do conjunto de colunas.

Este exemplo funciona com o SQL Server 2008 (10.0.x) ou posterior. Para obter mais informações sobre colunas esparsas, consulte Suporte a colunas esparsas no SQL Server Native Client.

Exemplo

Verifique se a variável de ambiente INCLUDE inclui o diretório que contém sqlncli.h.

#include <stddef.h>  
#include <comdef.h>  
#include <msdasc.h>  
#include <sqlncli.h>  
  
#define CHECKED(_hr) \  
   do { \  
      if (FAILED(hr =_hr)) { \  
         PrintHR(hr); \  
         goto ERR; \  
      } \  
   } while (0)  
  
#define CHECK_NOT_NULL(x) \  
   do { \  
      if((x) == NULL) { \  
         PrintHR(E_OUTOFMEMORY); \  
         goto ERR; \  
      } \  
   } while(0)  
  
#define SAFE_RELEASE(pI) \  
   do { \  
      if (pI) { \  
         pI->Release(); \  
         pI = 0; \  
      } \  
   } while(0)  
  
#define PROVIDER_FREE(pv) \  
   do { \  
      if (pv) { \  
         CoTaskMemFree(pv); \  
         pv = NULL; \  
      } \  
   } while(0)  
  
#define PRINT_FLAGS(f,m) \  
   do { \  
      if ((f & m) == m) \  
         wprintf(L"%ls, ", L#m); \  
   } while(0)  
  
#define PrintHR(hr) PrintHR_internal(hr, __FILE__, __LINE__)  
  
#define CHECKED3(_hr,_Obj,_IID) \  
   do { \  
      if (FAILED(hr = _hr)) { \  
         DumpErrorInfo(_Obj,_IID); \  
         goto ERR; \  
      } \  
   } while(0)  
  
void PrintHR_internal(HRESULT hr, char * szFile, ULONG uLine) {  
   wprintf(L"Error HR = %d (%x) %hs(%d)\n", hr, hr, szFile, uLine);  
}  
  
// DumpErrorInfo queries error interfaces, retrieving available status or error information.  
void DumpErrorInfo ( IUnknown* pObjectWithError, REFIID IID_InterfaceWithError ) {  
   // Interfaces used in the example.  
   IErrorInfo * pIErrorInfoAll = NULL;  
   IErrorInfo * pIErrorInfoRecord = NULL;  
   IErrorRecords * pIErrorRecords = NULL;  
   ISupportErrorInfo * pISupportErrorInfo = NULL;  
   ISQLErrorInfo * pISQLErrorInfo = NULL;  
   ISQLServerErrorInfo * pISQLServerErrorInfo = NULL;  
  
   // Number of error records.  
   ULONG nRecs;  
   ULONG nRec;  
  
   // Basic error information from GetBasicErrorInfo.  
   ERRORINFO errorinfo;  
  
   // IErrorInfo values.  
   BSTR bstrDescription;  
   BSTR bstrSource;  
  
   // ISQLErrorInfo parameters.  
   BSTR bstrSQLSTATE;  
   LONG lNativeError;  
  
   // ISQLServerErrorInfo parameter pointers.  
   SSERRORINFO * pSSErrorInfo = NULL;  
   OLECHAR * pSSErrorStrings = NULL;  
  
   // Hard-code an English (United States) locale for the example.  
   DWORD MYLOCALEID = 0x0409;  
  
   // Only ask for error information if the interface supports it.  
   if (FAILED(pObjectWithError->QueryInterface(IID_ISupportErrorInfo, (void**) &pISupportErrorInfo))) {  
      wprintf(L"SupportErrorErrorInfo interface not supported\n");  
      return;  
   }  
  
   if (FAILED(pISupportErrorInfo->InterfaceSupportsErrorInfo(IID_InterfaceWithError))) {  
      wprintf(L"InterfaceWithError interface not supported\n");  
      return;  
   }  
  
   // Do not test the return of GetErrorInfo. It can succeed and return  
   // a NULL pointer in pIErrorInfoAll. Simply test the pointer.  
   GetErrorInfo(0, &pIErrorInfoAll);  
  
   if (pIErrorInfoAll != NULL) {  
      // Test to see if it's a valid OLE DB IErrorInfo interface exposing a list of records.  
      if (SUCCEEDED(pIErrorInfoAll->QueryInterface(IID_IErrorRecords, (void**) &pIErrorRecords))) {  
         pIErrorRecords->GetRecordCount(&nRecs);  
  
         // Within each record, retrieve information from each of the defined interfaces.  
         for (nRec = 0; nRec < nRecs; nRec++) {  
            // From IErrorRecords, get the HRESULT and a reference to the ISQLErrorInfo interface.  
            pIErrorRecords->GetBasicErrorInfo(nRec, &errorinfo);  
            pIErrorRecords->GetCustomErrorObject(nRec,IID_ISQLErrorInfo, (IUnknown**) &pISQLErrorInfo);  
  
            // Display the HRESULT, then use the ISQLErrorInfo.  
            wprintf(L"HRESULT:\t%#X\n", errorinfo.hrError);  
  
            if (pISQLErrorInfo != NULL) {  
               pISQLErrorInfo->GetSQLInfo(&bstrSQLSTATE, &lNativeError);  
  
               // Display the SQLSTATE and native error values.  
               wprintf(L"SQLSTATE:\t%s\nNative Error:\t%ld\n", bstrSQLSTATE, lNativeError);  
  
               // SysFree BSTR references.  
               SysFreeString(bstrSQLSTATE);  
  
               // Get the ISQLServerErrorInfo interface from ISQLErrorInfo before releasing the reference.  
               pISQLErrorInfo->QueryInterface( IID_ISQLServerErrorInfo, (void**) &pISQLServerErrorInfo);   
  
               pISQLErrorInfo->Release();  
            }  
  
            // Test to ensure the reference is valid, then get error information from ISQLServerErrorInfo.  
            if (pISQLServerErrorInfo != NULL) {  
               pISQLServerErrorInfo->GetErrorInfo(&pSSErrorInfo, &pSSErrorStrings);  
  
               // ISQLServerErrorInfo::GetErrorInfo succeeds even when it has nothing to return.   
               // Test the pointers before using.  
               if (pSSErrorInfo) {  
                  // Display the state and severity from the returned information.   
                  // The error message comes from IErrorInfo::GetDescription.  
                  wprintf(L"Error state:\t%d\nSeverity:\t%d\n", pSSErrorInfo->bState, pSSErrorInfo->bClass);  
  
                  // IMalloc::Free needed to release references on returned values.  
                  CoTaskMemFree(pSSErrorStrings);  
                  CoTaskMemFree(pSSErrorInfo);  
               }  
  
               pISQLServerErrorInfo->Release();  
            }  
  
            if (SUCCEEDED(pIErrorRecords->GetErrorInfo(nRec, MYLOCALEID, &pIErrorInfoRecord))) {  
               // Get the source and description (error message) from the record's IErrorInfo.  
               pIErrorInfoRecord->GetSource(&bstrSource);  
               pIErrorInfoRecord->GetDescription(&bstrDescription);  
  
               if (bstrSource != NULL) {  
                  wprintf(L"Source:\t\t%s\n", bstrSource);  
                  SysFreeString(bstrSource);  
               }  
  
               if (bstrDescription != NULL) {  
                  wprintf(L"Error message:\t%s\n", bstrDescription);  
                  SysFreeString(bstrDescription);  
               }  
  
               pIErrorInfoRecord->Release();  
            }  
         }  
         pIErrorRecords->Release();  
      }  
      else {  
         // IErrorInfo is valid; get the source and description to see what it is.  
         pIErrorInfoAll->GetSource(&bstrSource);  
         pIErrorInfoAll->GetDescription(&bstrDescription);  
  
         if (bstrSource != NULL) {  
            wprintf(L"Source:\t\t%s\n", bstrSource);  
            SysFreeString(bstrSource);  
         }  
  
         if (bstrDescription != NULL) {  
            wprintf(L"Error message:\t%s\n", bstrDescription);  
            SysFreeString(bstrDescription);  
         }  
      }  
  
      pIErrorInfoAll->Release();  
   }  
   else   
      wprintf(L"GetErrorInfo has not returned ErrorInfo.\n");  
  
   pISupportErrorInfo->Release();  
   return;  
}  
  
void Test_GetRowset(IDBSchemaRowset *pdbSchemaRowset, DBCOUNTITEM cExpectedRows) {  
   HRESULT hr;  
   IRowset * pRowset = NULL;  
   IAccessor * pAccessor = NULL;  
   HACCESSOR hAccessor = NULL;  
  
   struct sRowData {  
      wchar_t wszColumnName [128];  
      VARIANT_BOOL fIsSparse;  
      VARIANT_BOOL fIsColumnSet;  
   } rowData;  
  
   DBBINDING rgBindings[3] = {  
      {4, offsetof(sRowData, wszColumnName), 0, 0, 0, 0, 0,  
      DBPART_VALUE,DBMEMOWNER_CLIENTOWNED, DBPARAMIO_NOTPARAM, sizeof(rowData.wszColumnName),0, DBTYPE_WSTR, 0, 0},  
      {41, offsetof(sRowData, fIsSparse),0, 0, 0, 0, 0,  
      DBPART_VALUE,DBMEMOWNER_CLIENTOWNED, DBPARAMIO_NOTPARAM, sizeof(rowData.fIsSparse),   0, DBTYPE_BOOL, 0, 0},  
      {42, offsetof(sRowData, fIsColumnSet),0, 0, 0, 0, 0,  
      DBPART_VALUE,DBMEMOWNER_CLIENTOWNED, DBPARAMIO_NOTPARAM, sizeof(rowData.fIsColumnSet),0, DBTYPE_BOOL, 0, 0}  
   };  
  
   DBCOUNTITEM iRow;  
   BSTR bstrTable = SysAllocString(L"tbl_sparse_test");  
  
   CHECK_NOT_NULL(bstrTable);  
  
   tagVARIANT rgRestrictions[3];  
   VariantInit(rgRestrictions);  
   VariantInit(rgRestrictions+1);  
   VariantInit(rgRestrictions+2);  
   rgRestrictions[0].vt = VT_EMPTY;  
   rgRestrictions[1].vt = VT_EMPTY;  
   rgRestrictions[2].vt = VT_BSTR;  
   rgRestrictions[2].bstrVal = bstrTable;  
  
   wprintf(L"\nTesting %ls\n",  cExpectedRows == 3 ? L"DBSCHEMA_COLUMNS_EXTENDED" : L"DBSCHEMA_SPARSE_COLUMN_SET");  
  
   CHECKED(pdbSchemaRowset->GetRowset(   
      NULL,  
      cExpectedRows == 3 ?  
      DBSCHEMA_COLUMNS_EXTENDED: DBSCHEMA_SPARSE_COLUMN_SET,  
      3,  
      rgRestrictions,  
      IID_IRowset,  
      0,  
      NULL,  
      (IUnknown**)&pRowset)  
      );  
  
   DBCOUNTITEM cRowsObtained = 0;  
   HROW rgRows[3];  
   HROW * pRows = rgRows;  
  
   CHECKED(pRowset->GetNextRows( 0, 0, cExpectedRows, &cRowsObtained, &pRows));  
  
   if (cRowsObtained != cExpectedRows)   
      CHECKED(E_UNEXPECTED);  
  
   CHECKED(pRowset->QueryInterface(IID_IAccessor, (void**)&pAccessor));  
   CHECKED(pAccessor ->CreateAccessor( DBACCESSOR_ROWDATA, 3, rgBindings, sizeof(rowData), &hAccessor, NULL));  
  
   for (iRow = 0 ; iRow < cExpectedRows; iRow++) {  
      CHECKED(pRowset->GetData( rgRows[iRow], hAccessor, (void*)&rowData));  
  
      wprintf(L"Column %ls,\tIsSparse=%ls, \tIsColumnSet=%ls\n",  
         rowData.wszColumnName,  
         (rowData.fIsSparse    ? L"TRUE " : L"FALSE"),  
         (rowData.fIsColumnSet ? L"TRUE " : L"FALSE"));  
   }  
  
ERR:  
   if (bstrTable)   
      SysFreeString(bstrTable);  
   SAFE_RELEASE(pAccessor);  
   SAFE_RELEASE(pRowset);  
}  
  
int __cdecl main() {  
   HRESULT hr;  
   IDBInitialize * pIDBInit = NULL;  
   IDataInitialize * pIDI = NULL;  
   IDBCreateSession * pIDBCreateSession = NULL;  
   IDBCreateCommand * pIDBCreateCommand = NULL;  
   ICommandText * pCommand = NULL;  
   IDBSchemaRowset * pdbSchemaRowset = NULL;  
   IOpenRowset * pOpenRowset = NULL;  
   IColumnsInfo * pColumnsInfo = NULL;  
   ULONG cSchemas;  
   ULONG cFoundSchemas = 0;  
   GUID * rgSchemas = NULL;  
   ULONG * rgRestSupport = NULL;  
   DBID dbidSparse;  
   DBORDINAL cColumns, i;  
   WCHAR * pNameBuff = NULL;  
   DBCOLUMNINFO * prgColInfo = NULL;  
  
   CHECKED(CoInitializeEx(NULL, COINIT_MULTITHREADED));  
   CHECKED(CoCreateInstance(CLSID_MSDAINITIALIZE, NULL, CLSCTX_INPROC_SERVER, IID_IDataInitialize, (void**)&pIDI));  
   CHECKED(pIDI->GetDataSource(NULL, CLSCTX_INPROC_SERVER, L"Provider=SQLNCLI11; Integrated Security=SSPI; Data Source=.; Initial Catalog=tempdb", IID_IDBInitialize, (IUnknown**)&pIDBInit));  
   CHECKED(pIDBInit->Initialize());  
   CHECKED(pIDBInit->QueryInterface(IID_IDBCreateSession, (void**)&pIDBCreateSession));  
   CHECKED(pIDBCreateSession->CreateSession(NULL, IID_IDBCreateCommand, (IUnknown**)&pIDBCreateCommand));  
   CHECKED(pIDBCreateCommand->CreateCommand(NULL, IID_ICommandText, (IUnknown**)&pCommand));  
  
   // Drop the old table if it exists  
   CHECKED(pCommand->SetCommandText(DBGUID_DBSQL, L"if object_id('tempdb.dbo.tbl_sparse_test','U') is not null drop table tempdb.dbo.tbl_sparse_test"));  
   CHECKED(pCommand->Execute(NULL, IID_NULL, NULL, NULL, NULL));  
  
   // Create a new table  
   CHECKED(pCommand->SetCommandText(DBGUID_DBSQL, L"create table tempdb.dbo.tbl_sparse_test (col1 int SPARSE, col2 int, col3 XML column_set for all_sparse_columns)"));  
   CHECKED3(pCommand->Execute(NULL, IID_NULL, NULL, NULL, NULL), pCommand, IID_ICommandText);  
  
   // Insert a row into the table  
   CHECKED(pCommand->SetCommandText(DBGUID_DBSQL, L"insert tempdb.dbo.tbl_sparse_test (col1, col2) values (1,2)"));  
   CHECKED3(pCommand->Execute(NULL, IID_NULL, NULL, NULL, NULL), pCommand, IID_ICommandText);  
  
   // Let's check the schemas support  
   CHECKED(pIDBCreateCommand->QueryInterface(IID_IDBSchemaRowset, (void**)&pdbSchemaRowset));  
   CHECKED(pdbSchemaRowset->GetSchemas(&cSchemas, &rgSchemas, &rgRestSupport));  
  
   while (cSchemas--) {  
      if (rgSchemas[cSchemas]== DBSCHEMA_COLUMNS_EXTENDED ||  
         rgSchemas[cSchemas]== DBSCHEMA_SPARSE_COLUMN_SET) {  
         if (++cFoundSchemas == 2)  
            break;  
      }  
   }  
  
   if (cFoundSchemas != 2) {  
      wprintf(L"Found %d of expected 2 new DBSCHEMAs\n", cFoundSchemas);  
      goto ERR;  
   }  
  
   // Test the schemas:  
   Test_GetRowset(pdbSchemaRowset, 1);  
   Test_GetRowset(pdbSchemaRowset, 3);  
  
   // Test the column info  
   CHECKED(pIDBCreateCommand->QueryInterface(IID_IOpenRowset, (void**)&pOpenRowset));  
  
   dbidSparse.eKind = DBKIND_NAME;  
   dbidSparse.uName.pwszName = L"tbl_sparse_test";  
  
   // This will result in "select * from tbl_sparse_test"  
   CHECKED(pOpenRowset->OpenRowset( NULL, &dbidSparse, NULL, IID_IColumnsInfo, 0, NULL, (IUnknown**)&pColumnsInfo));  
  
   CHECKED(pColumnsInfo->GetColumnInfo(&cColumns, &prgColInfo, &pNameBuff));  
   wprintf(L"\nTesting GetColumnInfo:\n");  
  
   for ( i = 0 ; i < cColumns ; i++) {  
      wprintf(L"Column name: %ls, flags: ",prgColInfo[i].pwszName);  
      DWORD dwFlags = prgColInfo[i].dwFlags;  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_ISFIXEDLENGTH);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_WRITEUNKNOWN);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_WRITE);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_MAYBENULL);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_ISLONG);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_ISNULLABLE);  
      PRINT_FLAGS(dwFlags, DBCOLUMNFLAGS_SS_ISCOLUMNSET);  
  
      wprintf(L"\n");  
   }  
  
ERR:  
   PROVIDER_FREE(prgColInfo);  
   PROVIDER_FREE(pNameBuff);  
   SAFE_RELEASE(pColumnsInfo);  
   SAFE_RELEASE(pOpenRowset);  
   PROVIDER_FREE(rgSchemas);  
   PROVIDER_FREE(rgRestSupport);  
   SAFE_RELEASE(pdbSchemaRowset);  
   SAFE_RELEASE(pCommand);  
   SAFE_RELEASE(pIDBCreateCommand);  
   SAFE_RELEASE(pIDBCreateSession);  
   SAFE_RELEASE(pIDI);  
   SAFE_RELEASE(pIDBInit);  
   CoUninitialize();  
}