When images are associated with database records, those images are usually stored on disk. The images are related to their respective records by storing their names in a table or perhaps by using the record's identifier as part of the file name. The advantages of storing images as files are performance (no database access needed to retrieve the file, and likely nothing but straight HTTP access), and flexibility.
But sometimes you may indeed need to store images within database tables (perhaps as blobs). Storing the images is easy enough, serving them dynamically is a little more complex. You can't simply use the column name in the IMG SRC attribute as you would static image files, although ColdFusion would indeed embed the image data within the tag, the browser would not display the image as intended.
When browsers render pages containing images they do so by making multiple requests, first for the page itself, and then for each image, making an HTTP request to obtain the URL named in the IMG SRC tag. But that URL need not be an actual file, it can also be a dynamic URL that returns an image.
Therefore, you can create a .cfm file that does nothing more than serve images. The code would work like this:
<!--- Get image --->
<cfquery datasource="mydsn" name="image">
<!--- Set MIME type to GIF or JPEG or ... --->
<cfcontent variable="image.imageData" ... >
This file would be saved on the server, and the URL to it (with the image identifier passed as a URL parameter) can now be used as an IMG SRC like this:
And that'll do it.