CREATE TABLE student(

  no int,

  ca varchar(20),

  name varchar(50),

  subject  varchar(50),

  scorce int

);

/* 数据 */

INSERT INTO student VALUES(1, '1班', '张三', '语文', 85);

INSERT INTO student VALUES(2, '1班', '张三', '数学', 90);

INSERT INTO student VALUES(3, '1班', '张三', '英语', 70);

INSERT INTO student VALUES(4, '1班', '李四', '语文', 70);

INSERT INTO student VALUES(5, '1班', '李四', '数学', 99);

INSERT INTO student VALUES(6, '1班', '李四', '英语', 62);

INSERT INTO student VALUES(7, '1班', '王五', '语文', 82);

INSERT INTO student VALUES(8, '1班', '王五', '数学', 74);

INSERT INTO student VALUES(9, '1班', '王五', '英语', 89);

INSERT INTO student VALUES(10, '2班', '刘晓希', '语文', 77);

INSERT INTO student VALUES(11, '2班', '刘晓希', '数学', 99);

INSERT INTO student VALUES(12, '2班', '刘晓希', '英语', 80);

INSERT INTO student VALUES(13, '2班', '朱鹏', '语文', 87);

INSERT INTO student VALUES(14, '2班', '朱鹏', '数学', 86);

INSERT INTO student VALUES(15, '2班', '朱鹏', '英语', 76);

INSERT INTO student VALUES(16, '2班', '欧阳雪', '语文', 91);

INSERT INTO student VALUES(17, '2班', '欧阳雪', '数学', 83);

INSERT INTO student VALUES(18, '2班', '欧阳雪', '英语', 77);

-- case when 实现

SELECT S.ca,

SUM(CASE WHEN S.subject='语文' THEN S.scorce ELSE 0 END) AS '语文',

SUM(CASE WHEN S.subject='数学' THEN S.scorce ELSE 0 END) AS '数学',

SUM(CASE WHEN S.subject='英语' THEN S.scorce ELSE 0 END) AS '英语'

FROM dbo.student AS S

GROUP BY S.ca

--pivot 实现

SELECT a.ca,

       [语文],

       [数学],

       [英语]

       INTO #StudentGroup  --导入临时表当中，UNPIVOT例子使用

FROM

(

    SELECT S.ca,

           S.subject,

           SUM(S.scorce) AS scorce

    FROM dbo.student AS S

    GROUP BY S.ca,

             subject

) AS S1

PIVOT

(

    SUM(S1.scorce)

    FOR S1.subject IN ([语文], [数学], [英语])

) a; 

-- UNPIVOT 实现

SELECT a.ca,

       a.科目,

       a.分数

FROM #StudentGroup AS SG UNPIVOT(分数 FOR 科目 IN([语文], [数学], [英语])) AS a;