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SQL>
SQL> CREATE TABLE major_stats (
2 major VARCHAR2(30),
3 total_credits NUMBER,
4 total_students NUMBER);
Table created.
SQL>
SQL> INSERT INTO major_stats (major, total_credits, total_students) VALUES ('Computer Science', 22, 3);
1 row created.
SQL>
SQL> INSERT INTO major_stats (major, total_credits, total_students) VALUES ('History', 12, 3);
1 row created.
SQL>
SQL> INSERT INTO major_stats (major, total_credits, total_students) VALUES ('Economics', 15, 2);
1 row created.
SQL>
SQL> INSERT INTO major_stats (major, total_credits, total_students) VALUES ('Music', 11, 2);
1 row created.
SQL>
SQL> INSERT INTO major_stats (major, total_credits, total_students) VALUES ('Nutrition', 16, 2);
1 row created.
SQL>
SQL>
SQL> CREATE TABLE students (
2 id NUMBER(5) PRIMARY KEY,
3 first_name VARCHAR2(20),
4 last_name VARCHAR2(20),
5 major VARCHAR2(30),
6 current_credits NUMBER(3)
7 );
Table created.
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER UpdateMajorStats
2 AFTER INSERT OR DELETE OR UPDATE ON students
3 DECLARE
4 CURSOR c_Statistics IS
5 SELECT major, COUNT(*) total_students,
6 SUM(current_credits) total_credits
7 FROM students
8 GROUP BY major;
9 BEGIN
10 DELETE FROM major_stats;
11
12 FOR v_StatsRecord in c_Statistics LOOP
13 INSERT INTO major_stats (major, total_credits, total_students)
14 VALUES (v_StatsRecord.major, v_StatsRecord.total_credits,
15 v_StatsRecord.total_students);
16 END LOOP;
17 END UpdateMajorStats;
18 /
Trigger created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10001, 'Scott', 'Lawson','Computer Science', 11);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major, current_credits)
2 VALUES (10002, 'Mar', 'Wells','History', 4);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10003, 'Jone', 'Bliss','Computer Science', 8);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10004, 'Man', 'Kyte','Economics', 8);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10005, 'Pat', 'Poll','History', 4);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10006, 'Tim', 'Viper','History', 4);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10007, 'Barbara', 'Blues','Economics', 7);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10008, 'David', 'Large','Music', 4);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10009, 'Chris', 'Elegant','Nutrition', 8);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10010, 'Rose', 'Bond','Music', 7);
1 row created.
SQL>
SQL> INSERT INTO STUDENTS (id, first_name, last_name, major,current_credits)
2 VALUES (10011, 'Rita', 'Johnson','Nutrition', 8);
1 row created.
SQL>
SQL> INSERT INTO students (id, first_name, last_name, major,current_credits)
2 VALUES (10012, 'Sharon', 'Clear','Computer Science', 3);
1 row created.
SQL>
SQL> select * from major_stats;
MAJOR TOTAL_CREDITS TOTAL_STUDENTS
------------------------------ ------------- --------------
Computer Science 22 3
Economics 15 2
Nutrition 16 2
History 12 3
Music 11 2
SQL>
SQL> drop table students;
Table dropped.
SQL> drop table major_stats;
Table dropped.
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