SQL Server 透视多个表

Question

我们有以下表格：

表 1：Student_Records
学生 ID     |课程 ID     |期间     |等级
12                       6010               P1                90

   23                       6020               P1                 80

   12                       6030               P2                ''空白，没有成绩

   15                       6010                P1                 70

   12                      6020               P1                 80

   15                       6020               P1                 90

表 2：Course_Records
CourseID        CourseDec       学分
6010                   数学              3

   6020                   生物学            3

   6030                 英语            3

表 3：Student_Info
StudentID         FirstName         LastName         ClassYear
12                       乔                  史密斯               2013

15                                                         李              2013

23                      皮特                   Vo               2013

结果愿望：
ClassYear           姓氏          名字           StudentId           数学          生物学
2013 Smith Joe 12 90 80

2013 Li Chak 15 70 90

如何使用 pivot 命令实现这个结果？

Answer 1

您可以为此使用 PIVOT，但它要求您知道自己感兴趣的课程描述。

SELECT p.classyear, 
       p.lastname, 
       p.firstname, 
       p.studentid, 
       pvt.math, 
       pvt.biology 
FROM   (SELECT sr.grade, 
               si.classyear, 
               si.studentid, 
               si.firstname, 
               silastname 
        FROM   student_info si 
               INNER JOIN student_records sr 
                 ON si.studentid = sr.studentid 
               INNER JOIN course_records cr 
                 ON sr.courseid = cr.courseid) p PIVOT ( AVG (grade) FOR 
       coursedec IN ( 
       [Math], [Biology]) ) AS pvt 
ORDER  BY pvt.classyear; 

Answer 2

通过连接查询出数字和课程，以便您最终得到

StudentID CourseDec Grade
1         Math      20
1         Woodwork  82

你最终得到的枢轴

StudentID Math WoodWork
1         20   82

然后加入 Back to student 以获取 First Name Alst Name 等。

Answer 3

https://data.stackexchange.com/stackoverflow/query/60493/http-stackoverflow-com-questions-9068600-sql-server-pivot-mulitple-tables

DECLARE @Student_Records AS TABLE (
  studentid INT,
  courseid  INT,
  period    VARCHAR(2),
  grade     INT);

INSERT INTO @Student_Records
VALUES      (12,
             6010,
             'P1',
             90),
            (23,
             6020,
             'P1',
             80),
            (12,
             6030,
             'P2',
             NULL),
            (15,
             6010,
             'P1',
             70),
            (12,
             6020,
             'P1',
             80),
            (15,
             6020,
             'P1',
             90);

DECLARE @Course_Records AS TABLE (
  courseid  INT,
  coursedec VARCHAR(50),
  credits   INT);

INSERT INTO @Course_Records
VALUES      ( 6010,
              'Math',
              3),
            ( 6020,
              'Biology',
              3),
            ( 6030,
              'English',
              3);

DECLARE @Student_Info AS TABLE (
  studentid INT,
  firstname VARCHAR(50),
  lastname  VARCHAR(50),
  classyear INT);

INSERT INTO @Student_Info
VALUES      (12,
             'Joe',
             'Smith',
             2013),
            (15,
             'Chak',
             'Li',
             2013),
            (23,
             'Pete',
             'Vo',
             2013);

SELECT DISTINCT coursedec
FROM   @Course_Records AS cr
       INNER JOIN @Student_Records sr
         ON sr.courseid = cr.courseid
WHERE  sr.grade IS NOT NULL;

SELECT classyear,
       lastname,
       firstname,
       summary.studentid,
       summary.math,
       summary.biology
FROM   (SELECT *
        FROM   (SELECT si.studentid,
                       coursedec,
                       grade
                FROM   @Course_Records AS cr
                       INNER JOIN @Student_Records sr
                         ON sr.courseid = cr.courseid
                       INNER JOIN @Student_Info si
                         ON si.studentid = sr.studentid
                WHERE  sr.grade IS NOT NULL) AS results PIVOT (AVG(grade) FOR
               coursedec
               IN (
               [Math], [Biology])) AS pvt) AS summary
       INNER JOIN @Student_Info si
         ON summary.studentid = si.studentid

请注意，随着更多课程的添加，您可以使用动态 HTML 来调整查询：

Pivot Table and Concatenate Columns