Mega Code Archive

Creating a Trigger with cursor inside

SQL> SQL> SQL> CREATE TABLE lecturer ( 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> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10001, 'Scott', 'Lawson','Computer Science', 11); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major, current_credits) 2 VALUES (10002, 'Mar', 'Wells','History', 4); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10003, 'Jone', 'Bliss','Computer Science', 8); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10004, 'Man', 'Kyte','Economics', 8); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10005, 'Pat', 'Poll','History', 4); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10006, 'Tim', 'Viper','History', 4); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10007, 'Barbara', 'Blues','Economics', 7); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10008, 'David', 'Large','Music', 4); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10009, 'Chris', 'Elegant','Nutrition', 8); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10010, 'Rose', 'Bond','Music', 7); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10011, 'Rita', 'Johnson','Nutrition', 8); 1 row created. SQL> SQL> INSERT INTO lecturer (id, first_name, last_name, major,current_credits) 2 VALUES (10012, 'Sharon', 'Clear','Computer Science', 3); 1 row created. SQL> SQL> CREATE TABLE major_stats ( 2 major VARCHAR2(30), 3 total_credits NUMBER, 4 total_lecturer NUMBER); Table created. SQL> SQL> SQL> CREATE OR REPLACE TRIGGER myTrigger 2 AFTER INSERT OR DELETE OR UPDATE ON lecturer 3 DECLARE 4 CURSOR c_Statistics IS 5 SELECT major, COUNT(*) total_lecturer, 6 SUM(current_credits) total_credits 7 FROM lecturer 8 GROUP BY major; 9 BEGIN 10 FOR v_StatsRecord in c_Statistics LOOP 11 UPDATE major_stats 12 SET total_credits = v_StatsRecord.total_credits, 13 total_lecturer = v_StatsRecord.total_lecturer 14 WHERE major = v_StatsRecord.major; 15 IF SQL%NOTFOUND THEN 16 INSERT INTO major_stats (major, total_credits, total_lecturer) 17 VALUES (v_StatsRecord.major, v_StatsRecord.total_credits, 18 v_StatsRecord.total_lecturer); 19 END IF; 20 END LOOP; 21 END myTrigger; 22 / Trigger created. SQL> SQL> drop table major_stats; Table dropped. SQL> drop table lecturer; Table dropped. SQL>