Sql 离子是不同的。 Student_Id Student_Name Maths English History Physics 1 ABC 93 89 90 70 2

离子是不同的。

Student_Id  Student_Name    Maths   English History Physics
1                ABC         93      89      90      70
2                XYZ         88      98      88      80
3                DEF         79      78      87      90

SQL> select * from student;

        ID NAM      MATHS    ENGLISH
---------- --- ---------- ----------
         1 ABC         93         89
         2 XYZ         88         98
         3 DEF         79         78

SQL> CREATE OR REPLACE FUNCTION f_sum (par_subject IN VARCHAR2)
  2     RETURN NUMBER
  3  IS
  4     l_str   VARCHAR2 (200);
  5     retval  NUMBER;
  6  BEGIN
  7     l_str :=
  8           'select sum('
  9        || DBMS_ASSERT.simple_sql_name (par_subject)
 10        || ') from student';
 11
 12     EXECUTE IMMEDIATE l_str INTO retval;
 13
 14     RETURN retval;
 15  END;
 16  /

Function created.

SQL> SELECT f_sum ('maths') FROM DUAL;

F_SUM('MATHS')
--------------
           260

SQL>

| SCORE | | ----: | | 93 | | GETSCORE('ABC','MATHS') | | ----------------------: | | 93 |

select (case when :input = 'Maths' then Maths
             when :input = 'English' then English
             when :input = 'History' then History
             when :input = 'Physics' then Physics
        end)  
from students
were Student_Name = 'ABC';

Student_Id    Student_Name
    1            ABC 
    . . .

Student_Id    Subject    Marks   
    1         Maths        93
    1         English      89
    1         History      90
    1         Physics      70
    . . .

select sm.marks
from studentmarks sm join
     students s
     on sm.student_id = s.student_id
where subject = :input;

SELECT      
      to_number(xmlquery('/ROWSET/ROW/C/text()'
        passing xmltype(dbms_xmlgen.getxml(
          'select '|| <subject_name> || ' as c '
          || 'from test_data WHERE student_name = ''' 
          || <student_name>  || ''''))
      returning content)) as marks
    FROM dual;