Assuming you're working in VisualStudio and not in Java, I would do something like the following:
1. Create a FileStream
2. Stream the contents of the db field containing the report out to a .rpt file.
3. Create a ReportDocument.
4. Use ReportDocument.Load to load the file you just saved.
5. Set the ReportSource of the viewer to the ReportDocument.
6. View the report.
-Dell