print STDOUT "<IMG SRC=\"show_pic.cgi\" action=showImage>";
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Why do you always explicitly print to STDOUT? That's unnecessary unless you've used select to change the default output filehandle.

You need to re-read the sugggest that you were given. "action" is a parameter to your CGI program. Therefore you should have this:

print STDOUT "<IMG SRC=\"show_pic.cgi?action=showImage\">";
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or (more idiomatically)

print qq(<IMG SRC="show_pic.cgi?action=showImage">);
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Then within show_pic.cgi you can check for the value of the "action" parameter and take appropriate action (i.e. returning either the HTML page or the image).
--
<http://www.dave.org.uk>

"The first rule of Perl club is you do not talk about Perl club."
-- Chip Salzenberg

okay, Im still being stupid :(
Have got rid of the print STDOUT's at least ! (I thought this was
needed, a web tutorial on CGI used print STDOUT)

I still don't get how my image path is fed to the show_pic.cgi
Must I access the database in show_pic.cgi rather than in the script that generates the html ?

sorry to be so thick ! Its a monday....
thanks for all your help