如何修改此工作的SQL SELECT / JOIN查询以删除重复项？

Question

我在修改它以删除重复记录时遇到麻烦。 在这种情况下，对于给定的meta_key，我具有三个具有相同meta_value的帖子，并且它返回了两个结果（GROUP BY可能有问题-仍在解决）。 但是，将第一个SELECT更改为DELETE无效。 这不是我要更改的部分，因此从两个表中都删除了数据吗？

$sql1 = "SELECT * 
         FROM (
             SELECT wp_posts.ID, wp_posts.post_title, wp_posts.post_type, wp_posts.post_status, wp_postmeta.meta_value 
             FROM wp_posts, wp_postmeta 
             WHERE wp_posts.ID=wp_postmeta.post_ID 
             AND post_type='banners' 
             AND post_status='publish' 
             AND meta_key='uselink' 
             AND meta_value='http://www.mylink.com/subpage/') 
         AS a 
         INNER JOIN ( 
             SELECT meta_value, MIN( post_id ) 
             AS min_id 
             FROM wp_postmeta 
             GROUP BY meta_value 
             HAVING COUNT( * ) > 1  ) 
         AS b 
         ON b.meta_value = a.meta_value 
         AND b.min_id <> a.id";

$result1 = $conn->query($sql1);

if ($result1->num_rows > 0) {
    while($row = $result1->fetch_assoc()) {
        echo $row["meta_value"] . ", ";
    }
} else {
    echo "0 results";
}

这是我尝试过的（不起作用）：

$sql1 = "DELETE * 
         FROM (
             SELECT wp_posts.ID, wp_posts.post_title, wp_posts.post_type, wp_posts.post_status, wp_postmeta.meta_value 
             FROM wp_posts, wp_postmeta 
             WHERE wp_posts.ID=wp_postmeta.post_ID 
             AND post_type='banners' 
             AND post_status='publish' 
             AND meta_key='uselink' 
             AND meta_value='http://www.mylink.com/subpage/') 
        AS a 
        INNER JOIN ( 
             SELECT meta_value, MIN( post_id ) 
             AS min_id FROM wp_postmeta 
             GROUP BY meta_value HAVING COUNT( * ) > 1  ) 
        AS b 
        ON b.meta_value = a.meta_value 
        AND b.min_id <> a.id";

我要离开的这个没有第二个有效的联接表：

DELETE a.* 
FROM wp_posts 
AS a 
INNER JOIN ( 
    SELECT post_title, MIN( id ) 
    AS min_id 
    FROM wp_posts 
    WHERE post_type = 'banners' 
    AND post_status = 'publish' 
    GROUP BY post_title HAVING COUNT( * ) > 1  ) 
AS b 
ON b.post_title = a.post_title AND b.min_id <> a.id 
AND a.post_type = 'banners' 
AND a.post_status = 'publish'

Answer 1

试试这个，（但是我不确定）

$sql1 = "DELETE p, pm
FROM wp_posts p
INNER JOIN wp_postmeta pm ON p.ID=pm.post_ID
WHERE p.post_type='banners'
AND p.post_status='publish'
AND pm.meta_key='uselink'
AND pm.meta_value='link'
AND (SELECT count(pm.meta_value) FROM
wp_postmeta pm
GROUP BY pm.meta_value
HAVING COUNT(*) > 1
WHERE pm.meta_value=p.meta_value)";