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Question

我有2个表，其中一个包含学生姓名和ID 学生

StdID | StdName
  1   |  'John'

seconed连续包含每个主题结果

stdresults

StdID  | SubjectID | SubjectName | Degree
 1     |      1    |   'English' |  90
 1     |      2    |   'Math'    |  86

我希望结果像这样

StdID | StdName | Subject1Degree | Subject2Degree | Subject ... Degree
  1      'John'         90               86            ....

无论主题数是多少

Answer 1

试试这个：

SELECT T1.STDID,
       T1.STDNAME,
       SUM(CASE WHEN (T2.SUBJECTNAME = 'ENGLISH' AND T2.SUBJECTID = 1) THEN 
              T2.DEGREE  ELSE 0 END) AS SUBJECT1DEGREE,
       SUM(CASE WHEN (T2.SUBJECTNAME = 'MATH' AND T2.SUBJECTID = 2) THEN 
             T2.DEGREE ELSE 0 END)AS SUBJECT2DEGREE
FROM STUDENTS T1, STDRESULTS T2
GROUP BY T1.STDID;

Demo