我不擅长SQL，但我当然在学习。
所以这个提供了wordpress帖子下面几个列表的内容。一个是“来自此用户的更受欢迎的文章”，另一个是“此类别中更受欢迎的文章。”
文章可以由编辑发布，也可以由登录或匿名用户提交。 它只是检查所有文章，看它们是来自同一个用户，还是与显示列表的帖子属于同一类别。当用户提交文章时，它仍然是“发布”，无论哪个管理员发布文章（因为它们必须首先被批准）。因此，当用户提交文章时，会有一个单独的数据库条目。
基本结构：
select post_id, post_title, post_name, (
//number of times this article has been
//favorited, to help sort them
) as favorited, (
//whether this article is from the same user
select count(*) > 0 from wp_users //have to put something, it's just a flag
where exists (
//see if this post was authored by the the same user(s)
and not exists (
//make sure it's not a user submitted article. If it is,
//we want to group it by the submitting user, not the
//approving editor
)
)
or exists (
//see if an 'original submitter username' exists for this post,
//and if so, see if it matches the post we're generating the list for
)
) as under_users, (
//see if this post is under the same category
) as under_category
我凌乱的查询：
select p.ID, p.post_title, p.post_name, (
select count(*)
from wp_usermeta as um
where um.meta_key = 'wpfp_favorites'
and POSITION(CONCAT("\"",p.ID,"\"") IN um.meta_value)
) as favorited, (
select count(*) > 0 from wp_users
where exists (
select *
from wp_terms as t, wp_term_taxonomy as tt, wp_term_relationships as tr
where tt.taxonomy = 'author'
and tr.object_id = p.ID
and tr.term_taxonomy_id = tt.term_taxonomy_id
and t.term_id = tt.term_id
and t.term_id in (
select t2.term_id
from wp_terms as t2, wp_term_taxonomy as tt2, wp_term_relationships as tr2
where tt2.taxonomy = 'author'
and tr2.object_id = 535
and tr2.term_taxonomy_id = tt2.term_taxonomy_id
and t2.term_id = tt2.term_id
)
and not exists (
select *
from wp_postmeta as pm
where pm.post_id = 535
and pm.meta_key = 'Original Submitter Username'
)
)
or exists (
select *
from wp_postmeta as pm
where pm.post_id = p.ID
and pm.meta_key = 'Original Submitter Username'
and pm.meta_value = (
select pm2.meta_value
from wp_postmeta as pm2
where pm2.post_id = 535
and pm2.meta_key = 'Original Submitter Username'
)
)
) as under_users, (
select count(*) > 0 from wp_users
where exists (
select *
from wp_terms as t, wp_term_taxonomy as tt, wp_term_relationships as tr
where tt.taxonomy = 'category'
and tr.object_id = p.ID
and tr.term_taxonomy_id = tt.term_taxonomy_id
and t.term_id = tt.term_id
and t.term_id in (
select t2.term_id
from wp_terms as t2, wp_term_taxonomy as tt2, wp_term_relationships as tr2
where tt2.taxonomy = 'category'
and tr2.object_id = 535
and tr2.term_taxonomy_id = tt2.term_taxonomy_id
and t2.term_id = tt2.term_id
and t2.term_id not in (3, 4)
)
)
) as under_category
from wp_posts as p
where p.post_type = 'post'
and p.ID != 535
and p.post_status = 'publish'
having (
under_users != 0
or under_category != 0
)
order by favorited desc
我觉得它可能会更短，更好，但我不知道该怎么做。我似乎在查询中多次查询同样的事情，我害怕添加任何其他东西（区分登录和匿名提交者，按视图和收藏夹排序文章等）以免崩溃在其本身，成为一个黑洞。
有任何提示可以帮助我吗？
答案 0 :(得分：3)
您可能最好在应用程序级别拆分其中一些子查询。然后，您可以将EXISTS条款更改为EXISTS IN (ids...)。
我发现MySQL中的嵌套子查询往往非常慢，因为需要一次检查的行数。破坏应用程序级别的子查询允许您使用缓存，并使您可以更好地控制子查询的操作，同时使SQL更易于阅读。
答案 1 :(得分：1)
不要过分担心您的查询是否复杂。在实际应用程序中，查询会像这样。如果它开始成为一个问题（记住你可以在SQL语句中嵌入注释），你可以创建视图来处理一些子查询。例如，under_category的子查询。你可以创建一个视图......
create view under_category_view as
select tr.object_id AS p_id
from wp_terms as t,
wp_term_taxonomy as tt,
wp_term_relationships as tr
where tt.taxonomy = 'category'
and tr.term_taxonomy_id = tt.term_taxonomy_id
and t.term_id = tt.term_id
and t.term_id in (select t2.term_id
from wp_terms as t2,
wp_term_taxonomy as tt2,
wp_term_relationships as tr2
where tt2.taxonomy = 'category'
and tr2.object_id = 535
and tr2.term_taxonomy_id = tt2.term_taxonomy_id
and t2.term_id = tt2.term_id
and t2.term_id not in (3, 4));
然后在您的大查询中，您将使用...
select count(*) > 0 from wp_users
where exists (select *
from user_category_view
where p_id = p.id) as under_category
顺便说一句，我发现垂直分割线并使用大缩进，因为我在这里做了有助于使粗略查询更容易阅读。