TSQL计数在多列中出现的次数

我有一个表格，其中每列都是一个问题，每行都是答案，可以假设值为1到4

计算每个问题每个答案出现次数的最有效方法是什么

输入表

q1  q2  q3
1   3   1
2   1   4
1   2   1

期望输出表

answer  q1  q2  q3

    1   2   0   2
    2   1   1   0
    3   0   1   0   
    4   0   0   1

到目前为止，我得出以下结论（针对第三季度的问题），但仅针对一个问题

CREATE TABLE #t
  (
    answer int
  )
insert into #t (answer) values (1)
insert into #t (answer) values (2)
insert into #t (answer) values (3)
insert into #t (answer) values (4)

select * into #q3 from (select q3 as q3,count(*) as occurenceq3
                    from [table]
                    group by q3) as x

select t.answer,tb.occurenceq3 as occurenceq3
from #t t left join #q3 tb on t.answer=tb.Q3

drop table #q3
drop table #t

我犯了一个错误，第一次尝试计数（*），但我认为聚合必须显式地位于被透视的列上是有意义的，即使我认为它们在逻辑上是等价的。

这应该可以：-

CREATE TABLE #question (q1 int, q2 int, q3 int)
INSERT INTO #question
VALUES
(1,3,1),
(2,1,4),
(1,2,1);

--unpivot to start with
WITH
UNPIVOTED AS
(
SELECT * 
FROM
    (SELECT q1,q2,q3
    FROM #question) p
UNPIVOT
    (answer FOR question in (q1,q2,q3)) AS unpvt
)

--Then pivot
SELECT * FROM 
(SELECT answer, question FROM unpivoted) p
PIVOT
(
COUNT(question)
FOR question IN (q1,q2,q3)
) as pvt

---

如果您想要最有效的方法，我建议在每个“q”列上放置一个索引，并按以下方式运行查询：

select a.answer,
       (select count(*) from #question q where q.q1 = a.answer) as q1,
       (select count(*) from #question q where q.q2 = a.answer) as q2,
       (select count(*) from #question q where q.q3 = a.answer) as q3
from (select 1 as answer union all select 2 union all select 3 union all select 4
     ) a;

这基本上是使用索引来计算值，并且应该非常快，比聚合所有未初始化的结果要快。

这将起作用

select t1.dis,
q1=(select count(q1) from CountAnswers where q1=t1.dis), 
q2=(select count(q2) from countAnswers where q2=t1.dis), 
q3=(select count(q3) from countAnswers where q3=t1.dis) 
from (select dis from( select q1 as dis from CountAnswers union select q2 as dis from CountAnswers union select q3 as dis from CountAnswers)mytab)t1; 

---

可能是取消pivot，然后pivot。可能您不能引用基表目录。我试图在SQL Fiddle上运行此操作，但该网站的行为与往常一样怪异。如果您返回原始帖子并用count（q）替换count（*），查询将正常工作。不幸的是，我没有很好地将语法提交到内存中。您是对的。我刚刚编辑过。非常感谢你们两位的支持。任何我可以研究这些东西的建议。Technet有一篇文章。这一个作为介绍可能更好：

select t1.dis,
q1=(select count(q1) from CountAnswers where q1=t1.dis), 
q2=(select count(q2) from countAnswers where q2=t1.dis), 
q3=(select count(q3) from countAnswers where q3=t1.dis) 
from (select dis from( select q1 as dis from CountAnswers union select q2 as dis from CountAnswers union select q3 as dis from CountAnswers)mytab)t1;