在 (Amazon Redshift) 中将 varchar 值的行转为列

Question

下面的table是一个id包含很多行的格式。

select id,name,value 
from table

"id","name","value"
"a1",newsletters,true
"a1",gdpr_marketing_opt_in,true
"a1",new_widget,true
"b2",newsletters,true
"b2",newsletters_2016,true
"c3",app_shell,true
"c3",sms_reminders,true
"c3",new_widget,true
"c3",online_booking,true
"c3",merchant_shiftplan,true

我想将上面的 table 转换为：

id newsletters  gdpr_marketing_opt_in new_widget  app_shell     sms_reminders   online_booking
a1    true           true              true        null            null              null
b2    true           null              null        null            null              null
c3    null           null              true        true            true              true

下面的代码returns语法错误：

SELECT *
from schema.table t
PIVOT
(
    max(value)
    FOR UG_LABEL IN ([newsletters], [gdpr_marketing_opt_in], [new_widget], [app_shell])
) p

Answer 1

在 Redshift 中，您可以像这样使用条件聚合：

select id, 
       max(case when name = 'newsletters' then value end) as newsletters,
       max(case when name = 'gdpr_marketing_opt_in' then value end) as gdpr_marketing_opt_in,
       max(case when name = 'new_widget' then value end) as new_widget,
       max(case when name = 'app_shell' then value end) as app_shell,
       max(case when name = 'sms_reminders' then value end) as sms_reminders,
       max(case when name = 'online_booking' then value end) as online_booking
from the_table
group by id;