Convert all dates stored in custom field

Question

I have a custom field to store the date of games, and I store it in database like

mm/dd/yyyy

Now I need to convert all dates to

dd/mm/yyyy

So how can do that?

Is timestamp a solution for it, if yes, how can do that

I need to change all old data to new data for 200 posts

Answer 1

Find the correct key for game_date_key and run this once:

global $wpdb;
$posts = $wpdb->get_results("SELECT ID FROM ".$wpdb->prefix."posts" WHERE post_type='post');
foreach ($posts as $post) {
    $old_date = get_post_meta($post->ID,'game_date_key',true);
    $new_date = date('d/m/Y', strtotime($old_date));
    update_post_meta($post->ID,'game_date_key',$new_date,$old_date);
}

(I assume you will have the sense to backup your database first just in case. :-)