Question

SELECT DISTINCT wposts.* 
    FROM wp_2_posts wposts, wp_2_postmeta wpostmeta, wp_2_postmeta wpostmeta1, wp_2_term_taxonomy, wp_2_terms, wp_2_term_relationships
    WHERE wposts.ID = wpostmeta.post_id
    AND wp_2_terms.term_id = '8'
    AND wp_2_term_taxonomy.term_id = wp_2_terms.term_id
    AND wp_2_term_taxonomy.term_taxonomy_id = wp_2_term_relationships.term_taxonomy_id
    AND wp_2_term_relationships.object_id = wposts.ID
    AND wpostmeta.meta_key = 'validity'
    AND wpostmeta.meta_value > '".$logic_date."'    
AND wpostmeta1.meta_key != 'permanent'  
    AND wposts.post_status = 'publish' 
    AND wposts.post_type = 'post'
    ORDER BY wposts.post_date DESC

到目前为止，很好的建议，继续使用第二个meta_key的“进化”查询！='permanent_listing'

SELECT wposts。* FROM wp_2_posts wposts LEFT JOIN wp_2_postmeta wpostmeta ON wposts.ID = wpostmeta.post_id LEFT JOIN wp_2_term_relationships wrelationships on wrelationships.object_id = wposts.ID LEFT JOIN wp_2_term_taxonomy wtaxonomy on wtaxonomy.term_taxonomy_id = wrelationships.term_taxonomy_id LEFT JOIN wp_2_terms wterms ON wtaxonomy.term_id = wterms.term_id 哪里 wterms.term_id ='--category id here--'AND wpostmeta.meta_key ='wpx_validity'AND wpostmeta.meta_value＆gt; ' - 今天约会 - '和 wpostmeta.meta_key！='permanent_listing'AND wposts.post_status ='发布'AND wposts.post_type ='post' ORDER BY wposts.post_date DESC

LEFT JOIN和INNER JOIN似乎做同样的事情。存在以下索引：wp_2_terms.term_id，wp_term_taxonomy.term_taxonomy_id，wp_2_term_relationships.object_id wp_2_postmeta有一个meta_id索引和字段：post_id，meta_key，meta_value。

此查询正在WPMU上运行。

Answer 1

首先，我建议您使用INNER JOIN语法来连接表：

SELECT table1.c1, table2.c2 FROM table1
  INNER JOIN table2 ON table1.ck = table2.ck

此外，您应该避免使用*运算符并仔细选择所需的列。 DISTINCT也会降低查询速度。你真的需要吗？

Answer 2

首先，您的wpostmeta1不会加入任何内容。

其次，您不需要DISTINCT，您需要IN。

试试这个：

SELECT  wposts.* 
FROM    wp_2_posts wposts
JOIN    wp_2_postmeta wpostmeta
ON      wpostmeta.post_id = wposts.ID
        AND wpostmeta.meta_key = 'validity'
        AND wpostmeta.meta_value > '".$logic_date."'
JOIN    wp_2_postmeta wpostmeta1,
ON      wpostmeta1.post_id = wposts.ID
        AND wpostmeta1.meta_key != 'permanent'  
WHERE   wposts.ID IN
        (
        SELECT  wp_2_term_relationships.object_id
        FROM    wp_2_term_relationships
        JOIN    wp_2_term_taxonomy
        ON      wp_2_term_taxonomy.term_taxonomy_id = wp_2_term_relationships.term_taxonomy_id
        WHERE   wp_2_term_taxonomy.term_id = '8'
        )
        AND wposts.post_status = 'publish' 
        AND wposts.post_type = 'post'
ORDER BYc
        wposts.post_date DESC

创建以下索引（或确保它们存在）：

wp_2_term_relationships (object_id, term_taxonomy_id)
wp_2_term_taxonomy (term_taxonomy_id, term_id)
wp_2_posts (post_status, post_type, post_date, id)

Answer 3

如果查询太慢，有不同的解决方案。

首先尝试创建一些索引，

然后尝试减少使用php过滤某些数据的连接。

如果它仍然很慢，可能是数据库模式错误，应该更改。

Answer 4

我敢打赌你5美元这是一个索引问题。我要做的第一件事就是确保你加入表格的所有字段都被编入索引。

如何优化此查询？

4 个答案: