SQL查询不返回结果

Question

我使用三类复选框来过滤来自WordPress的帖子（这个问题是关于查询的），我知道一个事实，我应该返回结果与以下查询（我生成第7行自动依据是什么在我的过滤器中选择'S）：

SELECT * FROM wp_posts 
LEFT JOIN wp_postmeta ON(wp_posts.ID = wp_postmeta.post_id) 
LEFT JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id) 
LEFT JOIN wp_term_taxonomy ON(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id) 
LEFT JOIN wp_terms ON(wp_terms.term_id = wp_term_taxonomy.term_id) 
WHERE 
    wp_terms.slug IN ('academia') AND wp_terms.slug IN ('early-career') 
    AND wp_term_taxonomy.taxonomy = 'jobtype' 
    AND wp_posts.post_status = 'publish' 
    AND wp_posts.post_type = 'jobs' 
GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC 

我至少有5个职位，有是在类别academia和early-career。

如果我改变第7行只是有一个IN声明，它过滤是一类就好：

wp_terms.slug IN ('academia','journalism') //More than one from same category 
AND wp_term_taxonomy.taxonomy = 'jobtype'...... 

它会发现，要么是学术界抑或新闻（正是我所期望的）的所有作业，但是当我在其他IN语句中添加时，不会返回任何内容（即使我的帖子与逻辑匹配）。

任何人都可以告诉我，如果有什么不对（可能是IN和值之间的空格？），因为我一直在这没有运气的日子。

任何帮助，非常感谢！谢谢！

P.S.如果有人想看看在现场，这是对（为看明白我的意思）：http://www.libertyguide.com/jobs

目前，我有一个全球性的，而不是OR任何IN的，直到我得到这个工作。

Answer 1

在IN子句中指定多个值表示该行必须匹配其中的一个值。指定2 IN子句指出该行必须匹配BOTH，这是不可能的（varchar不能同时是'学术'和'早期职业'）。

尝试添加以下到您的查询的末尾：

HAVING COUNT(*) > [NUMBER OF VALUES SELECTED] 

所以就变成：

SELECT * FROM wp_posts 
LEFT JOIN wp_postmeta ON(wp_posts.ID = wp_postmeta.post_id) 
LEFT JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id) 
LEFT JOIN wp_term_taxonomy ON(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id) 
LEFT JOIN wp_terms ON(wp_terms.term_id = wp_term_taxonomy.term_id) 
WHERE 
    wp_terms.slug IN ('academia', 'early-career') 
    AND wp_term_taxonomy.taxonomy = 'jobtype' 
    AND wp_posts.post_status = 'publish' 
    AND wp_posts.post_type = 'jobs' 
GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC 
HAVING COUNT(*) = 2 

Answer 2

SELECT * FROM wp_posts 
LEFT JOIN wp_postmeta ON(wp_posts.ID = wp_postmeta.post_id) 
LEFT JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id) 
LEFT JOIN wp_term_taxonomy ON(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id) 
LEFT JOIN wp_terms wt1 ON(wt1.term_id = wp_term_taxonomy.term_id) 
LEFT JOIN wp_terms wt2 ON(wt2.term_id = wp_term_taxonomy.term_id) 
WHERE 
    wt1.slug = 'academia' AND wt2.slug = 'early-career' 
    AND wp_term_taxonomy.taxonomy = 'jobtype' 
    AND wp_posts.post_status = 'publish' 
    AND wp_posts.post_type = 'jobs' 
GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC 

编辑 为了支持N类，你可以试试这个：

SELECT * FROM wp_posts 
LEFT JOIN wp_postmeta ON(wp_posts.ID = wp_postmeta.post_id) 
LEFT JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id) 
LEFT JOIN wp_term_taxonomy ON(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id) 
WHERE 
    wp_term_taxonomy.taxonomy = 'jobtype' 
    AND wp_posts.post_status = 'publish' 
    AND wp_posts.post_type = 'jobs' 
    AND wp_term_taxonomy.term_id IN (SELECT term_id from wp_terms where slug = 'academia') 
    AND wp_term_taxonomy.term_id IN (SELECT term_id from wp_terms where slug = 'early-career') 
GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC 

您可以根据需要在代码中多次添加AND wp_term_taxonomy ...行。