php - sql查詢結果合并的問題

問題描述

問題解答

從所提供的信息看，如果只是為了單純輸出文章ID，及對應的屬性10086和屬性12580的值，那么下面這個簡單的SQL就能實現

SELECT art.id, meta1.meta_value AS meta_key10086, meta2.meta_value AS meta_key12580FROM wp_posts AS art LEFT JOIN wp_postmeta AS meta1 ON meta1.post_id = art.id AND meta1.meta_key = ’10086’ LEFT JOIN wp_postmeta AS meta2 ON meta2.post_id = art.id AND meta2.meta_key = ’12580’回答2：

你要的是不是 GROUP_CONCAT 這個聚合函數？

試試用full join行不。未測試：

with m1 as (select * from meta where meta_key = ’10086’), m2 as (select * from meta where meta_key = ’12580’)select case m1.post_id when null then m2.post_id else m1.post_id end as post_id, m1.meta_value as meta_key_10086, m2.meta_value as meta_key_12580from m1 full join m2 on m1.post_id = m2.post_id and m1.meta_key=’10086’ and m2.meta_key=’12580’