Snowflake 中的数据透视字符串值

Question

我该如何调整这个 table

ID	attribute_name	attribute_value
1	Name	John
1	Country	UK
1	City	London

进入结构？

ID	Name	Country	City
1	John	UK	London

根据文档 pivot 需要一个聚合函数

 SELECT ...
   FROM ...
   PIVOT ( <aggregate_function> ( <pivot_column> )
            FOR <value_column> IN ( <pivot_value_1> [ , <pivot_value_2> ... ] ) )

如何将其应用于字符串值？

Answer 1

聚合函数可以是max()。例如：

select * 
from (
    select xx.seq, xx.value:"@id" id, xx.value:"$" title
    from BooksXML, table(flatten(xml:"$":"$")) xx
)
pivot(max(title) for id in ('bk101', 'bk102', 'bk103', 'bk104', 'bk105')) as p
order by seq

与table:

CREATE temp TABLE BooksXML
as
select parse_xml('<catalog issue="spring">
  <Books>
    <book id="bk101">The Good Book</book>
    <book id="bk102">The OK Book</book>
    <book id="bk103">The NOT Ok Book</book>
    <book id="bk104">All OK Book</book>
    <book id="bk105">Every OK Book</book>
  </Books>
</catalog>') xml
union all select parse_xml('
<catalog issue="spring">
  <Books>
    <book id="bk102">The OK Book1</book>
    <book id="bk103">The NOT Ok Book1</book>
    <book id="bk104">All OK Book1</book>
  </Books>
</catalog>')
union all select parse_xml('
<catalog issue="spring">
  <Books>
    <book id="bk101">The Good Book2</book>
    <book id="bk103">The NOT Ok Book2</book>
    <book id="bk104">All OK Book2</book>
    <book id="bk105">Every OK Book2</book>
  </Books>
</catalog>');