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

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

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

 STUDENTID       MARK RUNNING_AVERAGE
---------- ---------- ---------------
         1         55              55
         1         73              64
         2         39      55.6666667
         2         44           52.75
         2         63            54.8

5 rows selected.

SQL>
SQL>
SQL>
SQL>
SQL> drop table SAT;

Table dropped.