Code to make a post sticky

Question

How is it possible to upgrade a post to make it sticky directly from code, not by admin area? Is it possible through a code like:

update_post_meta($post_id, $meta_key, $meta_value, $prev_value);

In this case, the $post_id is known, but the $meta_key?

Thank you in advance for your answers

Answer 1

The sticky posts are saved as an array of post IDs in the wp_options table. Hence,

$stickies = get_option( 'sticky_posts' );
$stickies[] = $post_id;
update_option( 'sticky_posts', $stickies );

will make the post in question sticky.

EDIT:

Even better, the core provides functions to stick and unstick posts (had to have 'em).

stick_post( $post_id );
unstick_post( $post_id );

--> See source on trac