Question

假设我有这张表：

Name        Occupation
Samantha    Doctor
Julia       Actor
Maria       Actor
Meera       Singer
Ashely      Professor
Ketty       Professor
Christeen   Professor
Jane        Actor
Jenny       Doctor
Priya       Singer

我想要输出：

    Doctor     Professor    Singer   Actor
    Jenny       Ashley      Meera    Jane
    Samantha    Christeen   Priya    Julia
    NULL        Ketty       NULL     Maria

我想将占用行转换为列，然后按占用列出名称。我一直在尝试pivot关系运算符，但我们传递给pivot的第一个参数应该是一个聚合函数，所以我不确定这是否是解决此查询的最佳方法。这是我一直在使用pivot工作的查询，但当然我正在使用max(name)它只返回一个名称：

select * from occupations 
pivot (max(name) for occupation in ([doctor],[actor],[singer],[professor])) 
as pvt

这是我使用上述查询的输出：

doctor      actor   singer  professor
Samantha    Maria   Priya   Ketty

我可以使用pivot关系运算符来解决这个问题吗？我可以做些什么改变？

Answer 1

这个SQL

with data as (
    select * from (values
         ('Samantha', 'Doctor')
        ,('Julia',    'Actor')
        ,('Maria',    'Actor')
        ,('Meera',    'Singer')
        ,('Ashely',   'Professor')
        ,('Ketty',    'Professor')
        ,('Christeen','Professor')
        ,('Jane',     'Actor')
        ,('Jenny',    'Doctor')
        ,('Priya',    'Singer')
    )t(Name,Occupation)
),
groups as (
    select
        Name,Occupation,
        RowNo = row_number() over (partition by Occupation order by Name)
    from data
)
select
    Doctor,Professor,Singer,Actor
from groups
pivot (max(Name) for occupation in (Doctor,Professor, Singer,Actor) ) as pvt
;

的产率：

Doctor    Professor Singer    Actor
--------- --------- --------- ---------
Jenny     Ashely    Meera     Jane
Samantha  Christeen Priya     Julia
NULL      Ketty     NULL      Maria

Answer 2

我倾向于使用条件聚合来解决这些问题：

select max(case when occupation = 'Doctor' then Name end) as doctor,
       max(case when occupation = 'Actor' then Name end) as actor,
       max(case when occupation = 'Singer' then Name end) as singer,
       max(case when occupation = 'Professor' then Name end) as professor     
from (select t.*,
             row_number() over (partition by occupation order by name) as seqnum
      from thistable t
     ) t
group by seqnum
order by seqnum;

在tsql中使用pivot

2 个答案: