PRB: E_NOINTERFACE Returned from CRowset Move Methods

RESOLUTION

Either remove the extra BLOB column entry in the column map and the SELECT statement, or move the column into a separate accessor and access one BLOB field at a time. If the latter option is chosen, you must release the first ISequentialStream before getting the next ISequentialStream.

For example, the following code demonstrates how you might fetch two BLOB columns:

Sample Code

   class CTable1Accessor
   {
     public:
       TCHAR m_field1[51];
       ISequentialStream* m_pField2;
       ISequentialStream* m_pField3;
       BEGIN_ACCESSOR_MAP(CTable1Accessor, 2)
         BEGIN_ACCESSOR(0, true)
           COLUMN_ENTRY(1, m_field1)
           BLOB_ENTRY(2, IID_ISequentialStream, STGM_READ, m_pField2)
         END_ACCESSOR()
         BEGIN_ACCESSOR(1, false)
           BLOB_ENTRY(3, IID_ISequentialStream, STGM_READ, m_pField3)
         END_ACCESSOR()
       END_ACCESSOR_MAP()
       ...
   };
   void SomeFunc()
   {
      CTable1 t1;
      t1.Open();
      t1.MoveNext();
      // Read the data from t1.m_pField2 ISequentialStream *
      t1.m_pField2->Release(); // release ISequentialStream for first BLOB
      t1.GetData(1); // go get ISequentialStream for second BLOB
      ...
   }