Using Analytic Functions AVG(Mark) OVER (PARTITION BY StudentID ORDER BY StudentID, Mark) : OVER « Analytical Functions « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Analytical Functions
3. OVER

SQL>
SQL> CREATE TABLE SAT (
  2     StudentID  INT NOT NULL,
  3     ExamID     INT NOT NULL,
  4     Mark       INT,
  5     IfPassed   SMALLINT,
  6     Comments   VARCHAR(255),
  7     CONSTRAINT PK_SAT PRIMARY KEY (StudentID, ExamID));

Table created.

SQL>
SQL>
SQL> INSERT INTO SAT (StudentID,ExamID,Mark,IfPassed,Comments) VALUES (1,1,55,1,'Satisfactory');

1 row created.

SQL> INSERT INTO SAT (StudentID,ExamID,Mark,IfPassed,Comments) VALUES (1,2,73,1,'Good result');

1 row created.

SQL> INSERT INTO SAT (StudentID,ExamID,Mark,IfPassed,Comments) VALUES (2,3,44,1,'Hard');

1 row created.

SQL> INSERT INTO SAT (StudentID,ExamID,Mark,IfPassed,Comments) VALUES (2,5,39,0,'Simple');

1 row created.

SQL> INSERT INTO SAT (StudentID,ExamID,Mark,IfPassed) VALUES (2,6,63,1);

1 row created.

SQL>
SQL>
SQL> SELECT StudentID, Mark, AVG(Mark) OVER
  2  (PARTITION BY StudentID
  3   ORDER BY StudentID, Mark) Running_Avg_by_Student
  4  FROM SAT
  5  ORDER BY StudentID, Mark;

 STUDENTID       MARK RUNNING_AVG_BY_STUDENT
---------- ---------- ----------------------
         1         55                     55
         1         73                     64
         2         39                     39
         2         44                   41.5
         2         63             48.6666667

5 rows selected.

SQL>
SQL>
SQL> drop table SAT;

Table dropped.