将列转置为行

Question

我的table看起来像这样

SurveyId    comments    val paramid
123     test1       100 1
123     test2       200 2
123     test3       300 3
456     test10      200 1
456     test20      150 2
456     test30      320 3

我期待类似下面基于 paramid 的东西

surveyid    comments1   comments2   comments3   1   2   3
123     test1       test2       test3       100 200 300
456     test10      test20      test30      200 150 320

尝试如下使用枢轴

select * 
from 
(
SELECT       
     surveyid   
     ,val
      ,comments 
      ,paramid
  FROM sample_table where comments is not null and surveyid = 123
) a
pivot
(
  max([val])
  for [paramid] in ([1], [2], [3])
) piv;

有人可以告诉我上面的代码有什么问题吗？

Answer 1

你可以试试这个..它很简单，只使用一个 GROUP BY 子句。（在 MYSQL 中试过并且工作正常）

SELECT
surveyid
,MAX(comments1) AS comments1
,MAX(comments2) AS comments2
,MAX(comments3) AS comments3
,MAX(COL1) AS COL1
,MAX(COL2) AS COL2
,MAX(COL3) AS COL3
FROM
(
SELECT
surveyid
,CASE WHEN paramid=1 then comments else '' END AS comments1
,CASE WHEN paramid=2 then comments else '' END AS comments2
,CASE WHEN paramid=3 then comments else '' END AS comments3
,CASE WHEN paramid=1 then val else '' END AS COL1
,CASE WHEN paramid=2 then val else '' END AS COL2
,CASE WHEN paramid=3 then val else '' END AS COL3
FROM test.sample_table
) TMP
GROUP BY surveyid

结果： 123 测试 1 测试 2 测试 3 100 200 300 456 测试10 测试20 测试30 200 150 320

将列转置为行

transpose column to rows

sql

sql-server

pivot