取消雪花中的多个列

Question

我有一个表，如下所示：

我需要如下取消“评级”和“评论”：

在雪花中执行此操作的最佳方法是什么？

注意：评论列中有一些单元格为NULL

添加详细信息：

create or replace table reviews(name varchar(50), acting_rating int, acting_comments text, comedy_rating int, comedy_comments text);

insert into reviews values
    ('abc', 4, NULL, 1, 'NO'),
    ('xyz', 3, 'some', 1, 'haha'),
    ('lmn', 1, 'what', 4, NULL);
    
    select * from reviews;
    


select name, skill, skill_rating, comments
    from reviews
    unpivot(skill_rating for skill in (acting_rating,  comedy_rating)) 
    unpivot(comments for skill_comments in (acting_comments,comedy_comments)) 

--Following where clause is added to filter the irrelevant comments due to multiple unpivots

where substr(skill,1,position('_',skill)-1) = substr(skill_comments,1,position('_',skill_comments)-1) 
     order by name;

会产生预期的结果，但是对于具有NULL的数据，输出中将丢失具有NULL的未透视行：

NAME    SKILL   SKILL_RATING    COMMENTS
abc COMEDY_RATING   1   NO
lmn ACTING_RATING   1   what
xyz ACTING_RATING   3   some
xyz COMEDY_RATING   1   haha

Answer 1

这是一个基本脚本，应提供所需的输出

create or replace table reviews(name varchar(50), acting_rating int, acting_comments text, comedy_rating int, comedy_comments text);

insert into reviews values
    ('abc', 4, 'something', 1, 'NO'),
    ('xyz', 3, 'some', 1, 'haha'),
    ('lmn', 1, 'what', 4, 'hahaha');
    
    select * from reviews;
    


select name, skill, skill_rating, comments
    from reviews
    unpivot(skill_rating for skill in (acting_rating,  comedy_rating)) 
    unpivot(comments for skill_comments in (acting_comments,comedy_comments)) 

--Following where clause is added to filter the irrelevant comments due to multiple unpivots

where substr(skill,1,position('_',skill)-1) = substr(skill_comments,1,position('_',skill_comments)-1) 
     order by name;

Answer 2

如果您要解决的只是问题中指定的表-您可以使用一组UNION ALL手动进行处理：

select NAME
  , 'ACTING_RATING' as SKILL, ACTING_RATING as SKILL_RATING, ACTING_COMMENTS as SKILL_COMMENTS
from DATA
union all
select NAME
  , 'COMEDY_RATING', COMEDY_RATING, COMEDY_COMMENTS
from DATA
union all
select NAME
  , 'MUSICAL_PERFORMANCE_RATING', MUSICAL_PERFORMANCE_RATING, MUSICAL_PERFORMANCE_COMMENTS
from DATA