Question

我有这个专栏的表格：

[Student_ID],[Class_ID],[Techer_ID],[Course_ID],[Marks]

并且对于标记范围存在名称，例如：介于0到5之间= D. 在6到10之间= C 在11到15之间= B 在16到20之间= A

现在我需要创建T-Sq l Query for Return this result message columns：

Teacher_ID|Course_ID|Count(Marks)|Count(A)| Count(B)|Count(C)|Count(D)

非常感谢您的帮助

Answer 1

select  Teacher_ID
,       Course_ID
,       count(*)
,       sum(case when Marks between 16 and 20 then 1 end) as SumA
,       sum(case when Marks between 11 and 15 then 1 end) as SumB
,       sum(case when Marks between 6 and 10 then 1 end) as SumC
,       sum(case when Marks between 0 and 5 then 1 end) as SumD
from    YourTable
group by
        Teacher_ID
,       Course_ID

Answer 2

我会使用和Andomar相同的方法，只改变总数来算这样：

select  Teacher_ID
,       Course_ID
,       count(*)
,       count(case when Marks between 16 and 20 then 1 end) as countA
,       count(case when Marks between 11 and 15 then 1 end) as countB
,       count(case when Marks between 6 and 10 then 1 end) as countC
,       count(case when Marks between 0 and 5 then 1 end) as countD
from    YourTable
group by
        Teacher_ID
,       Course_ID

在我看来，查询看起来更自然。

Answer 3

你可以用PIVOT做到这一点。（另请注意，Marks-to-Letter计算的这种表述比必须键入每个范围的两端的一个更安全。）

with T as (
  select
    Teacher_ID,
    Course_ID,
    case
     when Marks <= 5 then 'countD'
     when Marks <= 10 then 'countC'
     when Marks <= 15 then 'countB'
    else 'countA' end as Letter
  from T
)
  select
    Teacher_ID,
    Course_ID,
    countD+countC+countB+countA as countMarks,
    countA,
    countB,
    countC,
    countD
  from T pivot (
    count(Letter) for Letter in ([countA],[countB],[countC],[countD])
  ) as P

AVG和Count从一列开始

3 个答案: