mysql - 值字段不存在 (MySQL)

Question

如果我运行这个查询:

SELECT
    wp_posts.ID,
    wp_posts.post_title,
    wp_posts.post_status,
    wp_postmeta.meta_key 
FROM
    wp_posts
    LEFT JOIN wp_postmeta ON wp_posts.ID = wp_postmeta.post_id 
WHERE
    post_type = 'product' AND 
    wp_postmeta.meta_key = 'cat_disabled' AND
    wp_postmeta.meta_value = 'on'

我得到 5348 条记录，但做相反的事情(获取 cat_disabled 键及其值未设置的记录，它需要永远:

SELECT
    wp_posts.ID,
    wp_posts.post_title,
    wp_posts.post_status,
    wp_postmeta.meta_key 
FROM
    wp_posts
    LEFT JOIN wp_postmeta ON wp_posts.ID = wp_postmeta.post_id 
WHERE
    post_type = 'product' AND 
    wp_postmeta.meta_key != 'cat_disabled' AND
    wp_postmeta.meta_value != 'on'

如何优化此查询以获取没有设置值 cat_disabled 的 meta_key 的产品。

Answer 1

没有所有的模式和一些数据来测试，这是一个建议:

SELECT
    wp_posts.ID,
    wp_posts.post_title,
    wp_posts.post_status,
    wp_postmeta.meta_key 
FROM
    wp_posts
LEFT JOIN wp_postmeta ON wp_posts.ID = wp_postmeta.post_id 
WHERE
    post_type = 'product' AND 
    wp_postmeta.post_id NOT IN
    (SELECT post_id 
    FROM wp_postmeta 
    WHERE meta_key = 'cat_disabled' AND
        meta_value = 'on')