private bool ReadInternal()
{
if (_endOfData)
{
return(false);
}
int rc;
int columnCount = _columnInfo.Length;
int i;
// Define each of the column buffers to Oracle, but only if it hasn't
// been defined before.
if (null == _buffer)
{
int templen = (_rowsToPrefetch > 1) ? _rowBufferLength : 0; // Only tell oracle about the buffer length if we intend to fetch more rows
NativeBuffer buffer = new NativeBuffer_RowBuffer(_rowBufferLength);
buffer.NumberOfRows = _rowsToPrefetch;
for (i = 0; i < columnCount; ++i)
{
_columnInfo[i].Bind(_statementHandle, buffer, ErrorHandle, templen);
}
_buffer = buffer;
}
// If we still have more data in the buffers we've pre-fetched, then
// we'll use it; we don't want to go to the server more than we absolutely
// have to.
if (_buffer.MoveNext())
{
return(true);
}
// If we've read the last buffer, and we've exhausted it, then we're
// really at the end of the data.
if (_isLastBuffer)
{
_endOfData = true;
return(false);
}
// Reset the buffer back to the beginning.
_buffer.MoveFirst();
// For LONG and LOB data, we have to do work to prepare for each row (that's
// why we don't prefetch rows that have these data types)
if (1 == _rowsToPrefetch)
{
for (i = 0; i < columnCount; ++i)
{
_columnInfo[i].Rebind(_connection);
}
}
// Now fetch the rows required.
Debug.Assert(0 < _rowsToPrefetch, "fetching 0 rows will cancel the cursor");
rc = TracedNativeMethods.OCIStmtFetch(
_statementHandle, // stmtp
ErrorHandle, // errhp
_rowsToPrefetch, // crows
OCI.FETCH.OCI_FETCH_NEXT, // orientation
OCI.MODE.OCI_DEFAULT // mode
);
// Keep track of how many rows we actually fetched so far.
int previousRowsTotal = _rowsTotal;
_statementHandle.GetAttribute(OCI.ATTR.OCI_ATTR_ROW_COUNT, out _rowsTotal, ErrorHandle);
if (0 == rc)
{
return(true);
}
if ((int)OCI.RETURNCODE.OCI_SUCCESS_WITH_INFO == rc)
{
_connection.CheckError(ErrorHandle, rc);
return(true);
}
if ((int)OCI.RETURNCODE.OCI_NO_DATA == rc)
{
int rowsFetched = _rowsTotal - previousRowsTotal;
if (0 == rowsFetched)
{
if (0 == _rowsTotal)
{
_hasRows = x_hasRows_False;
}
_endOfData = true;
return(false);
}
_buffer.NumberOfRows = rowsFetched;
_isLastBuffer = true;
return(true);
}
_endOfData = true;
_connection.CheckError(ErrorHandle, rc);
return(false);
}