MySQL Select with Inner Join, Limit only first

Question

我需要对数据库中的帖子进行分页，然后编写下一个查询:

SELECT posts.ID, posts.date, comments.name, comments.value 
FROM posts 
INNER JOIN comments 
    ON comments.ID = posts.ID 
INNER JOIN relations 
    ON relations.ID = posts.ID 
WHERE type_rel=1 AND status_post=1 AND 
LIMIT 0,10

问题在 LIMIT 语句中，我只需要限制“posts”表。

评论表有很多行，如果我将限制设置为“0,10”，则“帖子”表限制为 10 个帖子，但评论表也限制为 10 个。

有人能解决我的问题吗？我在 PHP 查询中使用它。

抱歉我的英语不好，提前致谢。

Answer 1

可以使用子查询限制结果集，然后加入:

SELECT 
  posts.ID, 
  posts.date, 
  comments.name, 
  comments.value 
FROM
  (SELECT * FROM posts WHERE status_post = 1 LIMIT 0,10) posts
LEFT JOIN 
  comments 
  ON comments.ID = posts.ID 
LEFT JOIN 
  relations 
  ON relations.ID = posts.ID AND relations.type_rel = 1

从评论来看，你索引文件中的查询是错误的，这是正确的:

SELECT 
  wp_posts.ID, 
  wp_posts.post_date, 
  wp_postmeta.meta_key, 
  wp_postmeta.meta_value 
FROM (SELECT * FROM wp_posts WHERE post_status="publish" AND post_type="post" LIMIT 0,2) wp_posts 
LEFT JOIN wp_postmeta 
  ON wp_postmeta.post_id = wp_posts.ID 
LEFT JOIN wp_term_relationships 
  ON wp_term_relationships.object_id = wp_posts.ID 
  AND wp_term_relationships.term_taxonomy_id=2

示例结果 here ，如您所见，您有两个帖子，id 1 和 5。

如果你想保留有 term_taxonomy_id = 2 的帖子，使用这个:

SELECT 
  wp_posts.ID, 
  wp_posts.post_date, 
  wp_postmeta.meta_key, 
  wp_postmeta.meta_value 
FROM (
  SELECT * 
  FROM wp_posts 
  JOIN wp_term_relationships 
  ON wp_term_relationships.object_id = wp_posts.ID 
  AND wp_term_relationships.term_taxonomy_id = 2
  WHERE post_status="publish" AND post_type="post" LIMIT 0,2) wp_posts 
LEFT JOIN wp_postmeta ON wp_postmeta.post_id = wp_posts.ID

Example here ，帖子 ID 为 5 和 7，限制为 0,1 仅返回 5。