SQL查詢不返回結果

Question

我使用三類複選框來過濾來自WordPress的帖子（這個問題是關於查詢的），我知道一個事實，我應該返回結果與以下查詢（我生成第7行自動依據是什麼在我的過濾器中選擇'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個職位，有是在類別academia和early-career。

如果我改變第7行只是有一個IN聲明，它過濾是一類就好：

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

它會發現，要麼是學術界抑或新聞（正是我所期望的）的所有作業，但是當我在其他IN語句中添加時，不會返回任何內容（即使我的帖子與邏輯匹配）。

任何人都可以告訴我，如果有什麼不對（可能是IN和值之間的空格？），因爲我一直在這沒有運氣的日子。

任何幫助，非常感謝！謝謝！

P.S.如果有人想看看在現場，這是對（爲看明白我的意思）：http://www.libertyguide.com/jobs

目前，我有一個全球性的，而不是OR任何IN的，直到我得到這個工作。

Answer 1

在IN子句中指定多個值表示該行必須匹配其中的一個值。指定2 IN子句指出該行必須匹配BOTH，這是不可能的（varchar不能同時是'學術'和'早期職業'）。

嘗試添加以下到您的查詢的末尾：

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

所以就變成：

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 

編輯 爲了支持N類，你可以試試這個：

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 

您可以根據需要在代碼中多次添加AND wp_term_taxonomy ...行。