MYSQL:基数违规:1242 子查询返回超过 1 行？

Question

我正在使用此查询来搜索标签相似性

SELECT sites_id
    FROM tags_to_sites
    WHERE tags_id IN (SELECT tags_id FROM tags_to_sites WHERE sites_id= ?)
    AND sites_id!= ?
    GROUP BY sites_id
    HAVING COUNT(*) = (  SELECT COUNT(*)  FROM  tags_to_sites
    WHERE tags_id IN (SELECT tags_id FROM tags_to_sites WHERE sites_id= ?)
      AND sites_id!= ?
    GROUP BY sites_id
    ORDER BY COUNT(*) DESC LIMIT 3)

但我收到错误

SQLSTATE[21000]: Cardinality violation: 1242 Subquery returns more than 1 row

有人知道为什么吗？

Answer 1

正确的查询

SELECT sites_id
    FROM tags_to_sites
    WHERE tags_id IN (SELECT tags_id FROM tags_to_sites WHERE sites_id= ?)
    AND sites_id!= ?
    GROUP BY sites_id
    HAVING COUNT(*) = (  SELECT COUNT(*)  FROM  tags_to_sites
    WHERE tags_id IN (SELECT tags_id FROM tags_to_sites WHERE sites_id= ?)
      AND sites_id!= ?
    GROUP BY sites_id
    ORDER BY COUNT(*) DESC LIMIT 1)
LIMIT 3