SQL行装列PIVOT和列转行UNPIVOT

数据

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);

行转列

-- 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; 

列转行

-- 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;