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我有兩個表:MySQL如何從同一列中選擇多個值以使它們出現在不同的列中?
wp_posts
ID post_title post_date
20 Título de tuit de ejemplo 2012-12-03 20:24:58
23 Título de teletipo de ejemplo 2012-12-04 13:56:33
25 Título de Clipping de ejemplo 2012-12-04 14:16:14
28 Título 4 diciembre 2012 2012-12-04 14:48:05
32 Título de noticia Actualidad 2012-12-04 17:35:57
78 Título de Destacado de ejemplo 2012-12-05 23:19:38
110 Título de Clipping radio 2012-12-09 15:57:28
112 Título de Clipping televisión 2012-12-09 15:59:31
而且wp_postmeta
meta_id post_id meta_key meta_value
61 20 wpcf-custom-author John Doe
134 28 wpcf-custom-author John Smith
85 23 wpcf-custom-author
111 25 wpcf-custom-author
176 32 wpcf-custom-author John Smith
614 110 wpcf-custom-author
524 78 wpcf-custom-author
627 112 wpcf-custom-author
538 80 wpcf-custom-author
48 20 wpcf-source
132 28 wpcf-source El País
83 23 wpcf-source El País
109 25 wpcf-source El País
174 32 wpcf-source El País
612 110 wpcf-source El Mundo
這是正確的,這些都是WordPress的表,但我的問題是關於MySQL的,我需要它檢索從wp_postmeta幾個字段屬於查詢相同的wp_posts.ID,這樣我就可以獲得同一行的所有信息。到目前爲止,我想出了:
SELECT DISTINCT posts.post_title AS title,
posts.post_date AS publish_date,
(SELECT subpostmeta.meta_value FROM wp_postmeta AS subpostmeta WHERE subpostmeta.post_id = postmeta.post_id AND subpostmeta.meta_key = 'wpcf-lead-in') AS lead_in,
(SELECT subpostmeta.meta_value FROM wp_postmeta AS subpostmeta WHERE subpostmeta.post_id = postmeta.post_id AND subpostmeta.meta_key = 'wpcf-custom-body') AS custom_body,
(SELECT subpostmeta.meta_value FROM wp_postmeta AS subpostmeta WHERE subpostmeta.post_id = postmeta.post_id AND subpostmeta.meta_key = 'wpcf-custom-author') AS custom_author,
(SELECT subpostmeta.meta_value FROM wp_postmeta AS subpostmeta WHERE subpostmeta.post_id = postmeta.post_id AND subpostmeta.meta_key = 'wpcf-source') AS source
FROM wp_posts AS posts, wp_postmeta AS postmeta
WHERE posts.ID = postmeta.post_id
AND posts.post_status = 'publish'
AND posts.post_type = 'contenido'
AND posts.post_date < NOW()
ORDER BY posts.post_date DESC
這是因爲據我所知工作正常,因爲我越來越:
post_title post_date lead_in custom_body custom_author source
Título de noticia de ejemplo 2013-02-04 15:10:25 En un lugar de la Mancha, de cuyo nombre no quiero... En un lugar de la Mancha, de cuyo nombre no quiero... Juan García ABC
Título de Clipping televisión 2012-12-09 15:59:31 Clipping TV: Your bones don't break, mine do. That... La Vanguardia
Título de Clipping radio 2012-12-09 15:57:28 Clipping radio: Now that we know who you are, I kn... El Mundo
Título de Destacado de ejemplo 2012-12-05 23:19:38 Really?! We'll go deliver this crate like professi...
但是我不知道這是否是最好的方法來得到我想要的,我已經閱讀了有關左連接並在過去使用它,但不知道我是否可以在這裏使用它或優點是什麼。
歡迎任何反饋!
編輯:我終於使用了左加入,所以我不知道如何投票或關閉此主題。它有一點比我先寫到這裏比較複雜,反正這是我的最終查詢:
SELECT DISTINCT posts.*,
posts.post_date AS publish_date,
tbl_lead_in.meta_value AS lead_in,
tbl_custom_author.meta_value AS custom_author,
tbl_source.meta_value AS source,
tbl_category_terms.slug AS category_term_slug,
tbl_category_terms.term_id AS category_term_id
FROM $wpdb->posts AS posts
LEFT JOIN $wpdb->postmeta AS tbl_lead_in
ON (posts.ID = tbl_lead_in.post_id
AND tbl_lead_in.meta_key = 'wpcf-lead-in')
LEFT JOIN $wpdb->postmeta AS tbl_custom_body ON
(posts.ID = tbl_custom_body.post_id
AND tbl_custom_body.meta_key = 'wpcf-custom-body')
LEFT JOIN $wpdb->postmeta AS tbl_custom_author
ON (posts.ID = tbl_custom_author.post_id
AND tbl_custom_author.meta_key = 'wpcf-custom-author')
LEFT JOIN $wpdb->postmeta AS tbl_source
ON (posts.ID = tbl_source.post_id
AND tbl_source.meta_key = 'wpcf-source')
LEFT JOIN $wpdb->term_relationships AS tbl_category_rel
ON (posts.ID = tbl_category_rel.object_id)
RIGHT JOIN $wpdb->term_taxonomy AS tbl_category
ON (tbl_category_rel.term_taxonomy_id = tbl_category.term_taxonomy_id
AND tbl_category.taxonomy = 'category')
LEFT JOIN $wpdb->terms AS tbl_category_terms
ON (tbl_category_terms.term_id = tbl_category.term_id)
WHERE posts.post_status = 'publish'
你可能想看看在轉動查詢。我在MySQL中對他們不太熟悉,所以我不能再幫忙。但谷歌搜索可以幫助。 – 2013-03-02 21:49:45