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rails 中的这个查询并没有结束。为什么？查询是：

    SELECT CONCAT(f.name, ' ', f.parent_names) AS FullName,
       stts.name AS 'Status',
       u.name AS Unit,
       city.name AS City,
       hus.mobile1 AS HusbandPhone,
       wife.mobile1 AS WifePhone,
       f.phone AS HomePhone,
       f.contact_initiation_date AS InitDate,
       fh.created_at AS StatusChangeDate,
       cmt.created_at AS CommentDate,
       cmt.comment AS LastComment,
       f.reconnection_date AS ReconnectionDate,
  (SELECT GROUP_CONCAT(t.name, ' ')
   FROM taggings tgs
   JOIN tags t ON tgs.tag_id = t.id
   WHERE tgs.taggable_type = 'family'
     AND tgs.taggable_id = f.id) AS HandlingStatus
FROM families f
JOIN categories stts ON f.family_status_cat_id = stts.id
JOIN units u ON f.unit_id = u.id
JOIN categories city ON f.main_city_cat_id = city.id
LEFT JOIN contacts hus ON f.husband_id = hus.id
LEFT JOIN contacts wife ON f.wife_id = wife.id
LEFT JOIN comments cmt ON f.id = cmt.commentable_id
AND cmt.created_at =
  (SELECT MAX(created_at)
   FROM comments
   WHERE commentable_id = f.id)
LEFT JOIN family_histories fh ON f.id = fh.family_id
AND fh.created_at =
  (SELECT MAX(created_at)
   FROM family_histories
   WHERE family_id = f.id
     AND family_history_cat_id = 1422)
AND fh.family_history_cat_id = 1422
WHERE 1=0
  OR (f.family_status_cat_id = 1422
      AND (  (SELECT MAX(_fh.created_at)
              FROM family_histories _fh
              WHERE _fh.family_history_cat_id = 1422
                AND _fh.family_id = f.id
                AND _fh.new_val LIKE '%1422%') BETWEEN '2010-03-10' AND '2011-03-02'))

我错过了什么吗？Synatx 是正确的，那么问题出在哪里？

4

1 回答 1

1

我认为问题是你有很多子查询。它必须花费很多时间。

我的建议是将通过子查询获得的一些信息存储在主表中。

或者，您始终可以尝试创建存储过程以加快该过程。

最好的祝福

于 2013-03-06T17:34:39.327 回答