FIX: CreateRelation Method Fails with Non-UNICODE Build

MORE INFORMATION

Sample Code to Demonstrate Fixed Code

   CMyDatabase db;
   db.Open("f:\\test\\relation\\relate.mdb");
   db.CreateRelation(_T("mytest"), _T("Table1"), _T("Table2"),
            dbRelationUnique|dbRelationUpdateCascade,_T("field1"),
            _T("field1"));
   db.Close();
				

   class CMyDatabase:public CDaoDatabase
   {
   public:
     void CreateRelation(LPCTSTR lpszName, LPCTSTR lpszTable,
                   LPCTSTR lpszForeignTable, long lAttributes,
                   LPCTSTR lpszField,
                   LPCTSTR lpszForeignField);
     void CreateRelation(CDaoRelationInfo& relinfo);
   };
				

   void CMyDatabase::CreateRelation(LPCTSTR lpszName, LPCTSTR lpszTable,
        LPCTSTR lpszForeignTable, long lAttributes, LPCTSTR lpszField,
        LPCTSTR lpszForeignField)
   {
     ASSERT_VALID(this);

     CDaoRelationInfo relinfo;
     CDaoRelationFieldInfo fieldinfo;

     relinfo.m_strName = lpszName;
     relinfo.m_strTable = lpszTable;
     relinfo.m_strForeignTable = lpszForeignTable;
     relinfo.m_lAttributes = lAttributes;
     relinfo.m_nFields = 1;

     relinfo.m_pFieldInfos = &fieldinfo;
     relinfo.m_pFieldInfos->m_strName = lpszField;
     relinfo.m_pFieldInfos->m_strForeignName = lpszForeignField;

     CreateRelation(relinfo);
   }

   void CMyDatabase::CreateRelation(CDaoRelationInfo& relinfo)
   {
     ASSERT_VALID(this);
     ASSERT(IsOpen());
     ASSERT(relinfo.m_nFields > 0);

     VARIANT var;
     var.vt    = VT_ERROR;
     var.scode = DISP_E_PARAMNOTFOUND;

     // Initialize relations collection so that relation can be
     // appended later
     if (m_pDAORelations == NULL)
         InitRelationsCollection();

     DAORelation* pDAORelation = NULL;
     DAOFields* pDAOFields = NULL;
     DAOField* pDAOField = NULL;

     // Create the relation
     DAO_CHECK(m_pDAODatabase->CreateRelation(
               COleVariant(relinfo.m_strName, VT_BSTRT),
               COleVariant(relinfo.m_strTable, VT_BSTRT),
               COleVariant(relinfo.m_strForeignTable, VT_BSTRT),
               COleVariant(relinfo.m_lAttributes), &pDAORelation));

     TRY
     {
        // Get the fields collection for later append of created field
        DAO_CHECK(pDAORelation->get_Fields(&pDAOFields));

        // Create field(s) and set the name and foreign name
        for (int nIndex = 0; nIndex < relinfo.m_nFields; nIndex++)
        {
            // note that we are using 'var' in the following function
            // instead of _afxOptionalVar declared in DAOCORE.CPP
            DAO_CHECK(pDAORelation->CreateField(
                    COleVariant(relinfo.m_pFieldInfos[nIndex].m_strName,
                                VT_BSTRT), var, var, &pDAOField));

           COleVariant var(relinfo.m_pFieldInfos[nIndex].m_strForeignName,
                           VT_BSTRT);
           DAO_CHECK(pDAOField->put_ForeignName(V_BSTR(&var)));

           // Append the field to relation fields collection and
           // release
           DAO_CHECK(pDAOFields->Append(pDAOField));
                     pDAOField->Release();
        }

        DAO_CHECK(m_pDAORelations->Append(pDAORelation));
     }
     CATCH_ALL(e)
     {
          // Clean up before throw
     if (pDAOField != NULL)
              pDAOField->Release();

          if (pDAOFields != NULL)
             pDAOFields->Release();

          pDAORelation->Release();
          THROW_LAST();
    }
    END_CATCH_ALL

    // Clean up
    if (pDAOField != NULL)
       pDAOField->Release();

    pDAOFields->Release();
    pDAORelation->Release();
   }