Need help creating a simple plugin add_action('publish_post'….)

I had created this plugin with some help here, but somehow it’s been lost from my local drive and server (computer change, as well as an unrelated accidental deletion of files from my server).

Here is what I’m trying to do:
Author writes Post and puts in Tags (usually names of basketball players).
Plugin gets the Tag ID and Slug.
Plugin copies the Tag ID to the matching name in a separate data table.

I’ve activated the plugin and tested it. I’m not getting any errors, but it’s not updating the other data table.

function save_post($post_ID)
{
mysql_select_db("jwrbloom_hhr");

 $wp_tagID = get_query_var('tag_id');
 $wp_slug = get_query_var('tag');

$query ="UPDATE wp_playerRank SET wpID = '$wp_tagID' WHERE wpSlug = '$wp_slug'";

   return $post_ID;
}

add_action('publish_post', 'save_post');