Add image links for 700 posts…

Hello,

I just imported the 700+ entries of my photoblog in a wordpress site. Each entry has been converted into a post where the content displays a photo with an <img> tag pointing to a photo. Each post points to a different photo.

I need to add a link for each image to the original image file.
I have a few notions of SQL and thought I could write an update query to change each post content and add an <a> tag around the <img> tag. The href portion of the link should be the same text as the src portion of the <img> tag. How can I retreive this part of the post content in a SQL query and change it for each post? Can someone help me with the code?
If this is too complicated, does anyone know a plugin that could add a link to an image in a post?

Thank you.