query to update post with featured images from array

Question

I have 100 existing posts of a custom post type that I need to update their featured images... How would I go about creating a query to randomly update these images from an array of say 20 images from the media library?

Any pointers would be great, thanks!

Answer 1

This is pseudo-code answer.

1. First get the posts you want with get_posts (you can pass the post_type as an argument)
2. Then get the ID of the images you want to set as thumnbail

3. Now do a loop and try with a query similar to this one:

   "UPDATE wp_postmeta SET meta_value = $image_id WHERE post_id = $post_id AND meta_key = ''_thumbnail_id''"

NOTE: To get the $image_id from the array of key you could use array_rand. You are gonna need wpdb to run the query.

Read the docs, and ask a question if you have any doubts.