MySQL PIVOT 和 JOIN 内部 MAX CASE

Question

我有两个表 domain 和 domain_meta。我想要完成的是 PIVOT 表 domain_meta （我能够做到）并将该表与域连接。但是我不能把我的头围绕如何将这些表与 PIVOT 和 MAX CASE 连接起来。对我的 domain_meta 表使用某种内部选择的最简单方法是什么？到目前为止，我的代码如下所示：

域

SELECT
*
FROM 
domain
ORDER BY id

domain_meta

SELECT
id,
domain_id,
source,
MAX(CASE WHEN (meta_key = 'domain') THEN meta_value ELSE NULL END) AS domain,
MAX(CASE WHEN (meta_key = 'ip') THEN meta_value ELSE NULL END) AS ip,
MAX(CASE WHEN (meta_key = 'link') THEN meta_value ELSE NULL END) AS link,
MAX(CASE WHEN (meta_key = 'net') THEN meta_value ELSE NULL END) AS net
FROM
domain_meta
GROUP BY id
ORDER BY id

domain domain_meta

Answer 1

类似的东西-

SELECT
  d.id,
  d.domain,
  MAX(CASE WHEN (dm.meta_key = 'domain') THEN dm.meta_value ELSE NULL END) AS domain,
  MAX(CASE WHEN (dm.meta_key = 'ip') THEN dm.meta_value ELSE NULL END) AS ip,
  MAX(CASE WHEN (dm.meta_key = 'link') THEN dm.meta_value ELSE NULL END) AS link,
  MAX(CASE WHEN (dm.meta_key = 'net') THEN dm.meta_value ELSE NULL END) AS net
FROM
  domain d
  LEFT JOIN domain_meta dm
    ON d.id = dm.domain_id
GROUP BY d.id