Sql 如何将数据行转换为列？

我有一个带有列的表

tblUser

userId，firstName，LastName，Mobile，…，QuestionID

我有另一个表，它的名称是

tblResults

，包含以下列

questionID、Question、choiceID、choice等

tblUser
-----------------------------------------------------------------------------
userID -  FirstName- LstName -Mobile  ...     ...     ... -  QuestionID -  ChiceID
-----------------------------------------------------------------------------
001   -   xx     -     yy   -   03212          -                   01        01 
001   -   xx     -     yy   -   03212          -                   02        02 
002   -   xxx     -    yyy  -   03425         -                    01        02 
002   -   xxx     -    yyy  -   03425        -                     02        01  
003   -   xxxx    -    yyyy  -  03429         -                    03        02 
003   -   xxxx   -     yyyy  -  03429          -                   03        01 
------------------------------------------------------------------------------

tblResults
---------------------------------------------------------------------
QuestionID   Question       ChoiceID       Chice    ....     ....            
---------------------------------------------------------------------
01        -    **Are you**   -  01   -   Male
01        -    **Areyou**    -  02    -  Female
02        -    **From**     -   01   -   xxxxx
02        -    **FROM**     -   02    -  yyyyy  
---------------------------------------------------------------------

我想得到下表所示的结果

-------------------------------------------------------------------------------
UserID FirstName LastName  Mobile  **Areyou**   **From**
-------------------------------------------------------------------------------
001    -   xx     -  yy     -   03212  -  Male  -  yyyyy
002    -   xxx    -  yyy    -   03425   - Female - xxxxx
003    -   xxxx   -  yyyy   -   03429  -  Female -  xxxxx        

您可以获得每个问题的唯一用户及其各自的选择，并为每个问题加入tblResults表一次：

select
  u.userID, u.FirstName, u.LastName, u.Mobile,
  q1.Choice as Areyou,
  q2.Choice as [From]
from (
  select userID, FirstName, LastName, Mobile,
  sum(case QuestionId when '01' then ChoiseId else 0 end) as ChoiseId1,
  sum(case QuestionId when '02' then ChoiseId else 0 end) as ChoiseId2
  from tblUser
) as u
inner join tblResults as q1 on q1.QuestionID = '01' and q1.ChoiseID = u.ChoiseId1
inner join tblResults as q2 on q2.QuestionID = '02' and q2.ChoiseID = u.ChoiseId2

同样，我们可以为每个问题创建一个表t（UserID，ChoiceID），然后内部连接所有这些表。然后我们得到（UserID，问题1的ChoiceID，问题2的ChoiceID，…）。加上用户信息，我们得到了理想的结果


select t1.UserID, t1.FirstName, t1.LastName, t1.Mobile, t1.Choice, t2.Choice
from 
  (select u.UserID, u.FirstName, u.LastName, u.Mobile, r.Choice
  from tblUser u, tblResults r 
  where u.questionID = '01' and u.QuestionID=r.QuestionID and u.ChoiceID = r.ChoiceID) t1
inner join 
  (select u.UserID UserID, r.Choice
  from tblUser u, tblResults r 
  where u.questionID = '02' and u.QuestionID=r.QuestionID and u.ChoiceID = r.ChoiceID) t2
/* 
inner join
  (...) t3
*/
on t1.UserID = t2.UserID /* and t2.UserID = t3.UserID */


您可以使用生成所需的结果。有两种方法，一种是对列进行硬编码的静态透视，另一种是在运行时获取列列表的动态透视

静态轴心：（请参阅）

动态轴心：（请参阅）

两者将产生相同的结果

create table tblUser
(
    userid int,
    fname varchar(10),
    lname varchar(10),
    mobile int,
    questionid int,
    choiceid int
) 
insert into tblUser values (001, 'xx', 'yy', 03212, 01, 01)
insert into tblUser values (001, 'xx', 'yy', 03212, 02, 02)
insert into tblUser values (002, 'xxx', 'yyy', 03425, 01, 02)
insert into tblUser values (002, 'xxx', 'yyy', 03425, 02, 01)
insert into tblUser values (003, 'xxxx', 'yyyy', 03429, 03, 02)
insert into tblUser values (003, 'xxxx', 'yyyy', 03429, 03, 01)

create table tblResults
(
    questionid int,
    question varchar(10),
    choiceid int,
    choice varchar(10)
)
insert into tblresults values (01, 'Are you', 01, 'Male')
insert into tblresults values (01, 'Are you', 02, 'Female')
insert into tblresults values (02, 'From', 01, 'xxxxx')
insert into tblresults values (02, 'From', 02, 'yyyyy')

select *
from 
(
    select u.userid,
        u.fname,
        u.lname,
        u.mobile,
        r.question,
        r.choice
    from tbluser u
    left join tblresults r
        on u.questionid = r.questionid
        and u.choiceid = r.choiceid
) x
pivot
(
    min(choice)
    for question in([are you], [from])
) p

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

SET @cols = STUFF((SELECT distinct ',' + QUOTENAME(c.question) 
            FROM tblresults c
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = 'SELECT userid, fname, lname, mobile, ' + @cols + ' from 
            (
                select u.userid,
                    u.fname,
                    u.lname,
                    u.mobile,
                    r.question,
                    r.choice
                from tbluser u
                left join tblresults r
                    on u.questionid = r.questionid
                    and u.choiceid = r.choiceid
           ) x
            pivot 
            (
                min(choice)
                for question in (' + @cols + ')
            ) p '


execute(@query)