顶部有匹配项的订单标签

Question

我从数据库中获取标签，我想对结果顶部的表tag_posts 中匹配的标签进行排序。它接近工作，但由于c_p_id 的组，我得到了重复。但是，如果我按顺序从组中删除c_p_id，有时会获取错误的行。使用一些 IF EXIST 选项是否更有意义？

我希望标签像这样列出：

TAG B
TAG A
TAG C

如果 TAG-B 在tag_posts 中有命中。

SELECT c_p_id, t_id, t_title
FROM tags
LEFT JOIN projects
ON p_id = " . $p_id . "
LEFT JOIN tag_posts
ON tp_t_id = t_id
LEFT JOIN cats
ON c_id = tp_c_id
AND c_p_id = p_id
GROUP BY t_id, c_p_id
ORDER BY c_p_id DESC, t_title ASC

// 编辑。我想出了一个不同的解决方案来做我想做的事：

SELECT t_id, t_title, 
    (SELECT 1 FROM tag_posts
        INNER JOIN cats
            ON c_id = tp_c_id
        INNER JOIN projects
            ON p_id = c_p_id
        WHERE tp_t_id = t_id
            AND p_id = " . $p_id . "
        LIMIT 1) used
FROM tags
ORDER BY used DESC, t_title ASC

Answer 1

解决方案：

SELECT t_id, t_title, 
    (SELECT 1 FROM tag_posts
        INNER JOIN cats
            ON c_id = tp_c_id
        INNER JOIN projects
            ON p_id = c_p_id
        WHERE tp_t_id = t_id
            AND p_id = " . $p_id . "
        LIMIT 1) used
FROM tags
ORDER BY used DESC, t_title ASC