sql-server - 基于范围的列数

Question

我有一个学生成绩表，其架构如下:

Student
--------
SNO
Marks

我想产生这样的结果:

MarksRange   Count
----------   ------
0             10
10             2
20             43
:              :
100            2

以上结果表明有:

• 10 名得零分的学生，
• 2 名学生如何获得 1 到 10 之间的分数，
• 43 从 11-20
• 等等。

谁能告诉我如何编写产生此结果的查询？

Answer 1

试试这个:

DECLARE @Student table (SNO int,Marks int)

INSERT INTO @Student VALUES (1, 0)
INSERT INTO @Student VALUES (1, 3)
INSERT INTO @Student VALUES (1, 45)
INSERT INTO @Student VALUES (1, 95)
INSERT INTO @Student VALUES (1, 85)
INSERT INTO @Student VALUES (1, 97)
INSERT INTO @Student VALUES (1, 92)

DECLARE @StartNumber int
       ,@EndNumber   int
SELECT @StartNumber=0
      ,@EndNumber=100

;WITH AllNumbers AS
(
    SELECT @StartNumber AS Number
    UNION ALL
    SELECT Number+10
        FROM AllNumbers
        WHERE Number<@EndNumber
)
SELECT
    n.number AS MarksRange,COUNT(s.SNO) AS CountOf
    FROM AllNumbers               n
        LEFT OUTER JOIN @Student  s ON s.Marks=n.Number OR (s.Marks>n.Number-10 AND s.Marks<=n.Number)
    GROUP BY n.number

输出:

MarksRange  CountOf
----------- -----------
0           1
10          1
20          0
30          0
40          0
50          1
60          0
70          0
80          0
90          1
100         3

如果您使用的不是 SQL Server 2005+，则需要将 CTE 替换为 Numbers table .并使用如下查询:

SELECT
    n.number,COUNT(s.SNO),0 AS CountOf
    FROM Numbers                  n
        LEFT OUTER JOIN @Student  s ON s.Marks=n.Number OR (s.Marks>n.Number-10 AND s.Marks<=n.Number)
    WHERE n.Number>=@StartNumber AND n.Number<=@EndNumber AND CONVERT(decimal(3,1),n.Number/10)=n.Number/10.0
    GROUP BY n.number