Question

这些是我的表

  CREATE TABLE student(
   student_id       NUMBER(4) PRIMARY KEY,
   name             Varchar2(18) );

   CREATE TABLE subject(
   subject_id       NUMBER(4) PRIMARY KEY,
   name             Varchar2(18) );

CREATE TABLE marksheet(
 id         NUMBER(4) , 
 student_id     NUMBER(4) REFERENCES student(student_id) NOT NULL,
 subject_id     NUMBER(4) REFERENCES subject(subject_id) NOT NULL,
 grade      VARCHAR2(1) NOT NULL,
 total_marks    NUMBER(3) NOT NULL,
 marks_obtain   NUMBER(3) NOT NULL   );



 insert into student values(2575, 'Tom');
 insert into student values(2576, 'jerry');

   INSERT INTO subject VALUES(10,'English');
   INSERT INTO subject VALUES(20,'Database');
   INSERT INTO subject VALUES(30,'Calculas'); 
   INSERT INTO subject VALUES(40,'OOAD');
   INSERT INTO subject VALUES(50,'Management');
   INSERT INTO subject VALUES(60,'java');


     INSERT INTO marksheet VALUES(1,2575,10,'A', 100, 80);
      INSERT INTO marksheet VALUES(1,2575,20,'A', 100, 80);
      INSERT INTO marksheet VALUES(1,2575,30,'A', 100, 80);
      INSERT INTO marksheet VALUES(1,2575,40,'A', 100, 80);
      INSERT INTO marksheet VALUES(1,2575,50,'A', 100, 80);

在标记表中插入数据

我想要的是它应该只显示

学生姓名一次
student_id一次
其余的标记表（等级，total_marks，marks_obtain）

Answer 1

使用row_number()并仅为编号为1的行显示ID和名称：

select case when rn = 1 then student_id end student_id,
       case when rn = 1 then name end name,
       subject_id, subject, grade, total_marks, marks_obtain
  from (
    select m.student_id, st.name, m.subject_id, sb.name subject, 
           m.grade, m.total_marks, m.marks_obtain,
           row_number() over (partition by m.student_id order by m.subject_id) rn
      from marksheet m
        join student st on st.student_id = m.student_id
        join subject sb on sb.subject_id = m.subject_id)

输出：

STUDENT_ID NAME               SUBJECT_ID SUBJECT            GRADE TOTAL_MARKS MARKS_OBTAIN
---------- ------------------ ---------- ------------------ ----- ----------- ------------
      2575 Tom                        10 English            A             100           80
                                      20 Database           A             100           80
                                      30 Calculas           A             100           80
                                      40 OOAD               A             100           80
                                      50 Management         A             100           80

我需要一个查询显示标记表在这里是我的表

1 个答案: