Presto 数据透视

发布于 2025-01-13 17:09:44 字数 602 浏览 1 评论 0原文

我对 Presto 很陌生，在其中旋转数据时遇到困难。我使用的方法如下：

select
distinct location_id,
case when role_group = 'IT' then employee_number end as IT_emp_num,
case when role_group = 'SC' then employee_number end as SC_emp_num,
case when role_group = 'HR' then employee_number end as HR_emp_num
from table
where 1=1
and id = 1234

这很好，但是，行中也填充了空值，我想旋转数据，只返回包含相关信息的一行。

我尝试使用 array_agg 函数，该函数会折叠数据，但也会保留空值（例如，它将为第一列返回 null,301166,null）

原文

I am really new to Presto and having trouble pivoting data in it.
The method I am using is the following:

select
distinct location_id,
case when role_group = 'IT' then employee_number end as IT_emp_num,
case when role_group = 'SC' then employee_number end as SC_emp_num,
case when role_group = 'HR' then employee_number end as HR_emp_num
from table
where 1=1
and id = 1234

This is fine, however, null values are also populated for the rows and I would like to pivot the data, to only return one row with the relevant info.

I have tried using the array_agg function, which will collapse the data but it also keeps the null values (e.g. it will return null,301166,null for the first colum)

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謸气贵蔟 2025-01-20 17:09:44

如果每个位置只需要一行，您可以使用 max 与分组依据：

select location_id, 
  max(IT_emp_num) IT_emp_num, 
  max(SC_emp_num) SC_emp_num, 
  max(HR_emp_num) HR_emp_num
from (
  select location_id,
    case when role_group = 'IT' then employee_number end as IT_emp_num,
    case when role_group = 'SC' then employee_number end as SC_emp_num,
    case when role_group = 'HR' then employee_number end as HR_emp_num
  from table
  where id = 1234)
group by location_id

If only one row per location is needed you can use max with group by:

select location_id, 
  max(IT_emp_num) IT_emp_num, 
  max(SC_emp_num) SC_emp_num, 
  max(HR_emp_num) HR_emp_num
from (
  select location_id,
    case when role_group = 'IT' then employee_number end as IT_emp_num,
    case when role_group = 'SC' then employee_number end as SC_emp_num,
    case when role_group = 'HR' then employee_number end as HR_emp_num
  from table
  where id = 1234)
group by location_id

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