Displaying an image from a database

I have created a content management system for a web site and want
some help with the most efficient way to display images that are
stored in a database.

The way, it seems, that php displays images in a web page is with a
link to a php "image" file with an image header and script which
displays the image. The the src of an <img> tag points to that file
and obtains the image for display on a web page. I have several
database tables containing records with images that need to be
displayed on various web pages.

At present, I have a separate image file for each database. I obtain
an image from each table by sending the record key to that file with a
GET. The "image" file then retrieves the image from the table it is
associated with using that key obtained via the GET and displays it.
This requires me to have a separate file for each table in the
database from which I retrieve images.

I'd like to simplify this, obtaining images from all tables with only
one "image" file, rather than one for each table. If I first retrieve
the image data and send it to a generic "image" file for display, it
means sending a lot of data to the file displaying the image, which is
often too much for a GET.

Another way I can do this is to send the appropriate query to the file
in a variable which the "image" page will use to retrieve and display
the image I need. I feel a bit insecure sending a valid query via a
GET. Otherwise, I could sent the key, tablename, and imagefieldname
via a GET that the image file assembles into a query for retrieving
the image. Same issue.

I keep thinking there must be a way to do this that is simpler, secure
and more efficient than the one I am attempting.

Can anyone help me figure out the most efficient and secure way to
accomplish what I am trying to do?

Thanks,

--Kenoli