I have found the following asp.net code to be very useful when serving files from a database:
Response.AppendHeader(\"content-disposition\", \"attachment; fi
Note that RFC 6266 supersedes the RFCs referenced below. Section 7 outlines some of the related security concerns.
The authority on the content-disposition header is RFC 1806 and RFC 2183. People have also devised content-disposition hacking. It is important to note that the content-disposition header is not part of the HTTP 1.1 standard.
The HTTP 1.1 Standard (RFC 2616) also mentions the possible security side effects of content disposition:
15.5 Content-Disposition Issues
RFC 1806 [35], from which the often implemented Content-Disposition
(see section 19.5.1) header in HTTP is derived, has a number of very
serious security considerations. Content-Disposition is not part of
the HTTP standard, but since it is widely implemented, we are
documenting its use and risks for implementors. See RFC 2183 [49]
(which updates RFC 1806) for details.