Question

我在理解获得以下结果集的最佳方法时遇到了一些困难。

我想要更新的结果集（数千行）：

ID    Question   Answer
---    --------  --------
1      Business    NULL
1      Job         Other
1      Location    UK
2      Business    Legal
3      Location    US
4      Location    UK

To This：

ID     Buisness   Job    Location  
---    --------   ---    --------
1      NULL       Other  UK
2      Legal      NULL   NULL
3      NULL       NULL   US
4      NULL       NULL   UK

我一直在关注SELF JOINS和PIVOT表，但想了解最好的方法，因为我无法达到所需的输出。

由于加里

Answer 1

如果你想使用pivot，你可以这样做：

CREATE TABLE #Table1
    ([ID] int, [Question] varchar(8), [Answer] varchar(5))
;

INSERT INTO #Table1
    ([ID], [Question], [Answer])
VALUES
    (1, 'Business', NULL),
    (1, 'Job', 'Other'),
    (1, 'Location', 'UK'),
    (2, 'Business', 'Legal'),
    (3, 'Location', 'US'),
    (4, 'Location', 'UK')
;

select * from 
(select * from #Table1) S
pivot (
  max(Answer) for Question in (Business, Job, Location)
) P

Answer 2

select
id,
max(case when question='business' then answer end) 'business',
max(case when question='Job' then answer end) 'Job',
max(case when question='Location' then answer end) 'Location'
group by id

将SQL行转换为列

2 个答案: