SQL查询:使用父组的Concat子元素组

时间:2014-11-19 22:01:44

标签: mysql sql sql-server wordpress parent-child

我正在尝试查询WordPress数据库以导出帖子及其内容列表。我有一切工作,但无法弄清楚如何包含附加的图像。我不确定如何将子项与同一个表中的父项关联起来。

父标识符位于名为ID的列中,子标识符位于名为post_parent的列中。我试图连接的值在一个名为guid的列中,它包含图像的完整URL(正是我需要的)。

wp_posts表格结构:

ID   post_parent   guid          post_type
1     0             http://...    attachment
2     1             http://...    attachment
3     1             http://...    attachment
4     1             http://...    attachment

以下是我的查询:

SELECT DISTINCT
post_title
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-year' AND wap_postmeta.post_id = wap_posts.ID) AS "Year"
,(SELECT group_concat(wap_terms.name separator ', ') 
FROM wap_terms
INNER JOIN wap_term_taxonomy ON wap_terms.term_id = wap_term_taxonomy.term_id
INNER JOIN wap_term_relationships wpr ON wpr.term_taxonomy_id = wap_term_taxonomy.term_taxonomy_id
WHERE taxonomy= 'car-manufacturer' AND wap_posts.ID = wpr.object_id
) AS "Manufacturer"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-model' AND wap_postmeta.post_id = wap_posts.ID) AS "Model"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-trim' AND wap_postmeta.post_id = wap_posts.ID) AS "Trim"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-vin' AND wap_postmeta.post_id = wap_posts.ID) AS "VIN"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-odometer' AND wap_postmeta.post_id = wap_posts.ID) AS "Odometer"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-price' AND wap_postmeta.post_id = wap_posts.ID) AS "Price"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-extcolor' AND wap_postmeta.post_id = wap_posts.ID) AS "Exterior Color"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-intcolor' AND wap_postmeta.post_id = wap_posts.ID) AS "Interior Color"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-transmission' AND wap_postmeta.post_id = wap_posts.ID) AS "Transmission"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-engine' AND wap_postmeta.post_id = wap_posts.ID) AS "Engine"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-fuel' AND wap_postmeta.post_id = wap_posts.ID) AS "Fuel Type"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-drivetrain' AND wap_postmeta.post_id = wap_posts.ID) AS "Drivetrain"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-doors' AND wap_postmeta.post_id = wap_posts.ID) AS "car-doors"
,(SELECT meta_value FROM wap_postmeta WHERE wap_postmeta.meta_key = 'car-stockno' AND wap_postmeta.post_id = wap_posts.ID) AS "Stock #"
,(SELECT group_concat(wap_terms.name separator ', ') 
FROM wap_terms
INNER JOIN wap_term_taxonomy ON wap_terms.term_id = wap_term_taxonomy.term_id
INNER JOIN wap_term_relationships wpr ON wpr.term_taxonomy_id = wap_term_taxonomy.term_taxonomy_id
WHERE taxonomy= 'car-feature' AND wap_posts.ID = wpr.object_id
) AS "Features"
,(SELECT group_concat(wap_terms.name separator ', ') 
FROM wap_terms
INNER JOIN wap_term_taxonomy ON wap_terms.term_id = wap_term_taxonomy.term_id
INNER JOIN wap_term_relationships wpr ON wpr.term_taxonomy_id = wap_term_taxonomy.term_taxonomy_id
WHERE taxonomy= 'car-body-type' AND wap_posts.ID = wpr.object_id
) AS "Body Type"

-- MY PROBLEM STARTS HERE
,(SELECT group_concat(wap_posts.guid separator ', ') 
FROM wap_posts
WHERE wap_posts.post_type = 'attachment' AND wap_posts.post_parent = wap_posts.ID
) AS "Images"
-- MY PROBLEM ENDS HERE

FROM wap_posts
WHERE post_type = 'vehicle' AND post_status = 'publish'
ORDER BY
post_title

我意识到这会返回NULL,因为附件的post_parent永远不会匹配它自己的ID。我只是不知道如何告诉查询将post_parent值与父亲的ID匹配,而不是它自己的ID。

希望我已经发布了足够的信息,请告诉我是否应该包含任何其他数据。谢谢你的阅读!

最诚挚的问候, 杰

1 个答案:

答案 0 :(得分:0)

你可以对同一张表做left join以产生所需的结果(假设不是每个帖子都有附件)

select     p.Id,group_concat(c.guid separator ', ') guids 
from wap_posts p
left join wap_posts c on (c.post_parent = p.id)

http://sqlfiddle.com/#!2/f7522/1/0