php - WordPress中SQL查询中的对角无序

Question

我在 WordPress 中执行 SQL 查询时遇到问题，我想将每个帖子 ID 放在带有 meta_key 列的一行中，但我得到了几个不均匀的记录。

SELECT P.ID,
     IF(PM.meta_key = 'nombrem', PM.meta_value, NULL) AS nombrem,
     IF(PM.meta_key = 'generom', PM.meta_value, NULL) AS generom,
     IF(PM.meta_key = 'tiempom', PM.meta_value, NULL) AS tiempom,
     IF(PM.meta_key = 'urlm', PM.meta_value, NULL) AS urlm,
     IF(PM.meta_key = 'imagenm', PM.meta_value, NULL) AS imagenm 
FROM K1nG_posts AS P
LEFT JOIN K1nG_postmeta AS PM ON ( P.ID = PM.post_id ) 
WHERE P.post_type = 'post' 
AND (P.post_status = 'publish' OR P.post_status = 'private')  ORDER BY P.post_date DESC

通过放置上面的代码，我在 phpmyadmin 中得到以下内容，我希望单个帖子 ID 将每个 meta_value 值都放在非对角线水平列中，如图所示。

Answer 1

您似乎在寻找条件聚合。为此，您需要添加一个 GROUP BY 子句并用聚合函数包围您的条件表达式:

SELECT P.ID,
    MAX(CASE WHEN PM.meta_key = 'nombrem' THEN PM.meta_value END) AS nombrem,
    MAX(CASE WHEN PM.meta_key = 'generom' THEN PM.meta_value END) AS generom,
    MAX(CASE WHEN PM.meta_key = 'tiempom' THEN PM.meta_value END) AS tiempom,
    MAX(CASE WHEN PM.meta_key = 'urlm'    THEN PM.meta_value END) AS urlm,
    MAX(CASE WHEN PM.meta_key = 'imagenm' THEN PM.meta_value END) AS imagenm
FROM 
    K1nG_posts AS P
    LEFT JOIN K1nG_postmeta AS PM ON P.ID = PM.post_id 
WHERE 
    P.post_type = 'post' 
    AND (P.post_status = 'publish' OR P.post_status = 'private')  
GROUP BY P.ID, P.post_date
ORDER BY P.post_date DESC