【问题标题】：need help with mysql query在mysql查询方面需要帮助
【发布时间】：2011-02-07 21:08:12
【问题描述】：

第一条背景信息：这是关于保存对象-对象关系及其在单个表中排序的cms，列是object_id，parent_id和排序顺序

第二块有几个连接的查询，我想按 2 个参数排序。其中之一是对象本身的排序，第二个是其父对象的排序顺序。

我现在的查询是：

SELECT obj_asset.*, object.headline AS title, oo.sort_order AS sort, op.sort_order FROM obj_asset 
JOIN object ON obj_asset.object_id = object.object_id 
JOIN object_object AS oo on obj_asset.object_id = oo.object_id
JOIN (SELECT sort_order from object_object WHERE object_id = (SELECT parent_id from object_object WHERE object_id = obj_asset.object_id )) AS op ON obj_asset.object_id = oo.object_id
WHERE obj_asset.profile_id = 140 AND obj_asset.rsvp_enabled = 1 AND object.is_published = 1 ORDER BY sort DESC;

而且它不起作用。不过这很好用：

SELECT obj_asset.*, object.headline AS title, oo.sort_order AS sort, op.sort_order FROM obj_asset 
JOIN object ON obj_asset.object_id = object.object_id 
JOIN object_object AS oo on obj_asset.object_id = oo.object_id
JOIN (SELECT sort_order from object_object WHERE object_id = (SELECT parent_id from object_object WHERE object_id = 11111 )) AS op ON obj_asset.object_id = oo.object_id
WHERE obj_asset.profile_id = 140 AND obj_asset.rsvp_enabled = 1 AND object.is_published = 1 ORDER BY sort DESC;

我得到的错误是：

1054 - “where 子句”中的未知列“obj_asset.object_id”

我怎样才能让它工作？

谢谢！

编辑：如果我能想出替代方法将父母排序到查询中，我可以解决这个问题。有没有这样的方法？

【问题讨论】：

您确定 obj_asset 表中有 object_id 列吗？
在这种情况下，错误消息是一个很好的线索。（如果解释器尝试使用错误的 object_id 字段，您可能必须使用 tablename.fieldname 命名样式。）:-)
@KomarSerjio - 是的，我是 - 正如你所看到的，它不是我使用相同列和表的唯一地方，如果我将其更改为实际 ID，它就可以工作。 @middaparka - 我明白为什么会出现错误 - 在内部选择的上下文中，没有 obj_asset.object_id 因为它还没有被选择......但是我怎样才能用一个查询来解决这个问题？

标签： mysql mysql-error-1054

【解决方案1】：

正如您已经发现的那样，问题在于您试图在子查询的约束中使用外部查询中的列：

  (SELECT sort_order
      from object_object
      WHERE object_id = (SELECT parent_id
                         from object_object
                         WHERE object_id = obj_asset.object_id )
     )

这个子查询可以重写，但不清楚如何只查看原始查询。

您的原始查询可能有错误（重新格式化）：

SELECT obj_asset.*, object.headline AS title, oo.sort_order AS sort, op.sort_order
FROM obj_asset 
JOIN object ON obj_asset.object_id = object.object_id 
JOIN object_object AS oo on obj_asset.object_id = oo.object_id
JOIN (SELECT sort_order
      from object_object
      WHERE object_id = (SELECT parent_id
                         from object_object
                         WHERE object_id = obj_asset.object_id )
     ) AS op ON obj_asset.object_id = oo.object_id
WHERE obj_asset.profile_id = 140 AND obj_asset.rsvp_enabled = 1 AND object.is_published = 1 ORDER BY sort DESC;

名为op 的子查询未在任何连接或where 子句中使用。

我的最佳猜测是您想要以下内容：

SELECT obj_asset.*, object.headline AS title, oo.sort_order AS sort, op.sort_order
FROM obj_asset 
JOIN object ON obj_asset.object_id = object.object_id 
JOIN object_object AS oo on obj_asset.object_id = oo.object_id
JOIN (SELECT sort_order, o2.object_id
    from object_object as o1
    INNER JOIN object_object as o2 ON o1.object_id = o2.parent_id
    ) AS op ON obj_asset.object_id = op.object_id
WHERE obj_asset.profile_id = 140 AND obj_asset.rsvp_enabled = 1 AND object.is_published = 1 ORDER BY sort DESC;

【讨论】：

伙计，我现在可以吻你了：P。这正是我所需要的。只有一个错误 - 应该是 (SELECT o1.sort_order.... 谢谢！
我很高兴它有帮助 - 请不要接吻，点赞就够了 :-)

【解决方案2】：

我认为你需要输入这个（包括 obj_asset 到 FROM）：

(SELECT parent_id FROM object_object, obj_asset  WHERE object_object.object_id = obj_asset.object_id )

但不是这个：

(SELECT parent_id from object_object WHERE object_id = obj_asset.object_id )

【讨论】：

不。这会产生全新的问题，因为 obj_asset 中没有 parent_id 并且它也会返回超过 1 行。

【解决方案3】：

您的子查询在 FROM 子句中不包含 obj_asset。

(SELECT parent_id FROM object_object WHERE object_id = obj_asset.object_id )

让那部分运行起来，你应该对整个事情有更好的运气。

只是一个提示...如果您在 SQL 语句中添加更多换行符和缩进，您会更容易发现问题。

【讨论】：

嗯？是的..我知道这就是问题所在。我只是想不出任何办法来解决它。
哎呀，我的意思是 FROM 子句。试试SELECT parent_id FROM object_object, obj_asset WHERE object_object.object_id = obj_asset.object_id
就像我对 SVGreg 的回答一样——这会引发新问题，因为 parent_id 不是 obj_asset 的列，如果是，那么 select 将返回多行，我只需要一个。