我正在处理一个查询，以平展wordpress数据库中的一些wp\u postsmeta数据，并需要为各种meta\u值设置一个特定值。我有一个类别键和各种类别值，对于每个值，我想为我们的品牌调色板设置一个名为color的列和一个名为color的列

select post_title as title, 
 MAX(CASE WHEN meta_key='corporate_calendar_category' THEN meta_value END) as 'category',
 MAX(CASE WHEN meta_key = 'corporate_calendar_subcategory' THEN meta_value END) as 'subcategory',

 // Do I need to include a nested CASE WHEN?
 MAX(CASE WHEN meta_key = 'corporate_calendar_subcategory' and meta_value = 'Marketing' THEN 'blueLagoon' END) as 'color',

 MAX(CASE WHEN meta_key = 'corporate_calendar_presenter' THEN meta_value END) as 'presenter',
 MAX(CASE WHEN meta_key = 'corporate_calendar_date' THEN meta_value END) as 'start_date',
 MAX(CASE WHEN meta_key = 'corporate_calendar_time' THEN meta_value END) as 'start_time',
 MAX(CASE WHEN meta_key = 'corporate_calendar_duration' THEN meta_value END) as 'duration',
 MAX(CASE WHEN meta_key = 'corporate_calendar_registration_link' THEN meta_value END) as 'registration_link',
 MAX(CASE WHEN meta_key = 'corporate_calendar_description' THEN meta_value END) as 'description',
 MAX(CASE WHEN meta_key = 'corporate_calendar_image_path' THEN meta_value END) as 'image_path'

FROM   wp_posts p 
JOIN wp_postmeta m ON p.id = m.post_id
where p.post_type = 'calendar-event'
and p.post_status = 'publish'
GROUP BY p.id

“公司日历”子类别有许多值，“市场营销”、“人力资源”、“公司假日”等，对于每个子类别，我希望每一行都有特定的颜色。

title     category   subcategory       color        presenter   start_date etc.
Example   Training   Marketing         blueLagoon   someone     08/29/2018
Labor Day Reminder   Company Holiday   camelot                  09/03/2018
etc
etc

实现这一点的最佳方法是在针对meta\ u值时使用嵌套case吗？还是有更好的办法？
我也尝试过包含if语句（如下），但每行都重复。

if(meta_key = 'corporate_calendar_subcategory', 
 CASE
   WHEN meta_value = 'Marketing' THEn 'blueLagoon'
   WHEN meta_value = 'Company Holiday' THEN 'camelot'
 END,
 '') as color,