1

我无法弄清楚如何让这个子查询工作以获取该行的最新日期。

SELECT Thread_Heading.*, Thread_Articles.*, Thread_ArticlesPost.* 
FROM Thread_Heading 
LEFT JOIN Thread_Articles 
    ON Thread_Articles.Thread_Article_Head_id=Thread_Heading.Thread_Head_id 
LEFT JOIN 
(
    SELECT Thread_ArticlesPost.* 
    FROM Thread_ArticlesPost 
    ORDER BY Thread_ArticlePost_DT DESC
) Thread_ArticlesPost 
    ON  Thread_ArticlesPost.Thread_ArticlePost_Article_id=Thread_Articles.Thread_Article_id  
WHERE Thread_Head_Level = '5' 
GROUP BY Thread_Heading.Thread_Head_id 
ORDER BY Thread_ArticlePost_DT DESC

我需要按每篇 Thread 文章的最新帖子来排序文章发布日期。相当新的 sql 和 php 我只是无法解决这个问题，任何帮助将不胜感激。

吨

ABLE: Thread_Heading | 
Thread_Head_id
Thread_Head_Name
Thread_Head_Type
Thread_Head_Creator
Thread_Head_Date
Thread_Head_Level

TABLE: Thread_Articles | 
Thread_Article_id
Thread_Article_Head_id
Thread_Article_Creator
Thread_Article_DT
Thread_Article_Level
Thread_Article_Type
Thread_Article_Title

TABLE: Thread_ArticlesPost | 
Thread_ArticlePost_id
Thread_ArticlePost_Head_id
Thread_ArticlePost_Article_id
Thread_ArticlePost_Creator
Thread_ArticlePost_DT
Thread_ArticlePost_Level
Thread_ArticlePost_Type
Thread_ArticlePost_Title
Thread_ArticlePost_Content

我需要像这样显示日期：

Head Name | Article title | ORDER BY LATEST ArticlePost DT | ArticlePost Creator

我使用左连接的原因是即使没有文章或文章回复也能获取左数据。

感谢帮助。

已经用它来显示数据感谢 Blue

SELECT *
FROM
( SELECT th.Thread_Head_Name,
ta. , tp1.maxdate, tp2. FROM Thread_Heading th LEFT JOIN Thread_Articles ta ON th.Thread_Head_id = ta.Thread_Article_Head_id LEFT JOIN
( SELECT max(Thread_ArticlePost_DT) maxDate,
Thread_ArticlesPost.* FROM Thread_ArticlesPost GROUP B Thread_ArticlePost_Article_id ) tp1 ON tp1.Thread_ArticlePost_Article_id=ta.Thread_Article_id
LEFT JOIN Thread_ArticlesPost tp2 ON tp1.Thread_ArticlePost_Article_id = tp2.Thread_ArticlePost_Article_id 和 tp1.maxdate = tp2.Thread_ArticlePost_DT
WHERE th.Thread_Head_Level = '5' ORDER BY tp1.maxdate DESC) m GROUP BY Thread_Head_Name ORDER BY Thread_ArticlePost_DT DESC

4

2 回答 2

3

如果没有看到您的完整表模式，您将需要执行类似的操作：

SELECT th.*, ta.*, tp.* 
FROM Thread_Heading th
LEFT JOIN Thread_Articles ta
    ON th.Thread_Head_id = ta.Thread_Article_Head_id
LEFT JOIN 
(
    SELECT max(Thread_ArticlePost_DT) maxDate, Thread_ArticlesPost.* 
    FROM Thread_ArticlesPost 
    GROUP BY Thread_ArticlePost_Article_id
) Thread_ArticlesPost tp
    ON  tp.Thread_ArticlePost_Article_id=ta.Thread_Article_id  
WHERE Thread_Head_Level = '5' 
GROUP BY th.Thread_Head_id 
ORDER BY tp.maxdate DESC

根据您的编辑，以下应返回您想要的数据：

SELECT th.Thread_Head_Name, 
  ta.Thread_Article_Title,
  tp1.maxdate,
  tp2.Thread_ArticlePost_Creator
FROM Thread_Heading th
LEFT JOIN Thread_Articles ta
    ON th.Thread_Head_id = ta.Thread_Article_Head_id
LEFT JOIN 
(
    SELECT max(Thread_ArticlePost_DT) maxDate, 
      Thread_ArticlesPost.Thread_ArticlePost_Article_id
    FROM Thread_ArticlesPost 
    GROUP BY Thread_ArticlePost_Article_id
) tp1
  ON  tp1.Thread_ArticlePost_Article_id=ta.Thread_Article_id  
LEFT JOIN Thread_ArticlesPost tp2
  ON tp1.Thread_ArticlePost_Article_id = tp2.Thread_ArticlePost_Article_id
  AND tp1.maxdate = tp2.Thread_ArticlePost_DT 
WHERE th.Thread_Head_Level = '5' 
ORDER BY tp1.maxdate DESC

编辑#2，根据您的评论，我认为下面的查询应该解决任何剩余的问题：

SELECT th.Thread_Head_id,
  th.Thread_Head_Name,
  ta.Thread_Article_Title,
  tp.Thread_ArticlePost_Creator,
  tap.MaxPostDate
FROM Thread_Heading th 
LEFT JOIN
(
  SELECT max(ta.Thread_Article_DT) MaxArticleDate, 
    ta.Thread_Article_Head_id,
    max(tp.Thread_ArticlePost_DT) MaxPostDate
  FROM Thread_Articles ta
  LEFT JOIN Thread_ArticlesPost tp
    ON ta.Thread_Article_id = tp.Thread_ArticlePost_Article_id
  GROUP BY Thread_Article_Head_id
) tap
  ON th.Thread_Head_id = tap.Thread_Article_Head_id 
LEFT JOIN Thread_Articles ta
  ON tap.Thread_Article_Head_id = ta.Thread_Article_Head_id
  AND tap.MaxArticleDate = ta.Thread_Article_DT
LEFT JOIN Thread_ArticlesPost tp
  ON tap.MaxPostDate = tp.Thread_ArticlePost_DT
WHERE th.Thread_Head_Level = '5'
ORDER BY MaxPostDate desc

请参阅带有演示的 SQL Fiddle

于 2012-08-23T22:16:38.570 回答
0

您不必GROUP BY在您的帖子之外有一个子句，您的帖子已经根据您的最新帖子分组在子查询中。试试这个，

SELECT  a.*, b.*, c.* 
FROM    Thread_Heading a
            LEFT JOIN Thread_Articles b
                ON b.Thread_Article_Head_id = a.Thread_Head_id
            LEFT JOIN Thread_ArticlesPost c
                ON c.Thread_ArticlePost_Article_id = b.Thread_Article_id 
            LEFT JOIN 
            (
                SELECT      Thread_ArticlePost_Article_id, MAX(Thread_ArticlePost_DT) maxDate
                FROM        Thread_ArticlesPost 
                GROUP BY    Thread_ArticlePost_Article_id
            ) d ON  d.Thread_ArticlePost_Article_id = b.Thread_Article_id AND
                    c.Thread_ArticlePost_DT = d.maxDate
WHERE       Thread_Head_Level = '5' 
-- GROUP BY a.Thread_Head_id 
ORDER BY    Thread_ArticlePost_DT DESC
于 2012-08-23T22:30:42.683 回答