MySQL下一行ORDER BY多列JOIN表2

Question

我需要帮助限制此查询的结果集。

SELECT tt.id
FROM kf_topics AS tt
LEFT JOIN kf_posts AS pp
ON tt.id = pp.topicid
WHERE tt.boardid = 1
GROUP BY tt.id
ORDER BY tt.sticky DESC, pp.time DESC

Current返回下面的数组。

但是，我需要在具有我指定ID的行之后的列表中找到行，请记住这些行将根据ORDER BY tt.sticky DESC，pp.time DESC更改命令ALOT。此外，行永远不会处于完美的ID顺序，因此将其置于ID字段上是不可能的。

例如，如果我想在ID = 24之后找到下一行，则查询结果将是ID =＆gt; 23

Answer 1

我们可以使用单个查询执行此操作，如下所示

SELECT ttid
FROM 
(SELECT tt.id ttid,@row:=@row+1 rownum,IF(tt.id=24,@j:=@row,0)
FROM kf_topics AS tt
LEFT JOIN kf_posts AS pp
ON tt.id = pp.topicid JOIN (SELECT @row:=0) AS rowcount
WHERE tt.boardid = 1
GROUP BY tt.id
ORDER BY tt.sticky DESC, pp.time DESC) A JOIN (SELECT @j+1 as rownum) B ON (A.rownum=B.rownum);

我不确定你为什么使用group by，但它无论如何都应该有用。

Answer 2

SET @row:=0;
SELECT rownum+1 INTO @nextrow FROM 
   (SELECT tt.id AS id, @row AS rownum
   FROM kf_topics AS tt
   LEFT JOIN kf_posts AS pp
   ON tt.id = pp.topicid
   WHERE tt.boardid = 1
   AND (@row:=@row+1)<=1
   GROUP BY tt.id
   ORDER BY tt.sticky DESC, pp.time DESC) A
WHERE A.id=<id>)
SET @row=0;
SELECT A.id FROM 
  (SELECT tt.id AS id, @row AS rownum
   FROM kf_topics AS tt
   LEFT JOIN kf_posts AS pp
   ON tt.id = pp.topicid
   WHERE tt.boardid = 1
   AND (@row:=@row+1)<=1
   GROUP BY tt.id
   ORDER BY tt.sticky DESC, pp.time DESC) A 
WHERE A.rownum=@nextrow

这可以重写为单个查询。上述查询未进行优化，但会提供您需要的结果。我会再考虑并尝试发布opmized查询。