WordCamp Vienna Workshop

INSERT INTO wp_custom_meta (post_id, post_hide_from_archive, _user_rate_mean)
SELECT 
    p.ID AS post_id,
    COALESCE(CAST(meta1.meta_value AS UNSIGNED), 0) AS post_hide_from_archive,
    COALESCE(CAST(meta2.meta_value AS FLOAT), 0) AS _user_rate_mean
FROM 
    wp_posts p
LEFT JOIN 
    wp_postmeta meta1 
    ON p.ID = meta1.post_id 
    AND meta1.meta_key = 'post_hide_from_archive'
LEFT JOIN 
    wp_postmeta meta2 
    ON p.ID = meta2.post_id 
    AND meta2.meta_key = '_user_rate_mean'
WHERE 
    p.post_type = 'post'
    AND p.post_status = 'publish'
GROUP BY 
    p.ID;