Add photo credit to each post

Hi,

I have more than 1500 posts on my wordpress. Each post has a photo in it and I was to credit the same to the agency I got these images from. How can I acheive this quicly without editing each post?

I want something like “Photos: This Person” at the end of each post. Can this be done via a query in Database?

Even better if this can be done by a field as later if I get images from another person I can credit him too.

Please provide a database query.

I know this can be done via editing template but it will not work if I want to credit more than 1 agency.