Generating Web Content from Query Results - MySQL - page 641

my $size = ( stat ( $fh ))[ 7 ];
read ( $fh , $data , $size ) == $size
or error ( "Failed to read entire file $image_path: $!" );
$fh -> close ();
}
$dbh -> disconnect ();
# Send image to client, preceded by Content-Type: and Content-Length:
# headers.
print header ( - type => $type , - Content_Length => length ( $data ));
print $data ;
19.8. Serving Banner Ads
Problem
You want to display banner ads by choosing images on the fly from a set of images.
Solution
Use a script that selects a random row from an image table and sends the image to the
client.
Discussion
The display_image.pl script shown in Recipe 19.7 assumes that the URL contains a
parameter that names the image to be sent to the client. Another application might
determine which image to display for itself. One popular image-related use for web
programming is to serve banner advertisements for display in web pages. A simple way
to do this is by means of a script that picks an image at random each time it is invoked.
The following Python script, banner.py , shows how to do this, where the “ads” are the
flag images in the image table:
#!/usr/bin/python
# banner.py: serve randomly chosen banner ad from image table
# (sends no response if no image can be found)
import cookbook
conn = cookbook . connect ()
stmt = "SELECT type, data FROM image ORDER BY RAND() LIMIT 1"
cursor = conn . cursor ()
cursor . execute ( stmt )
row = cursor . fetchone ()
cursor . close ()