sql trigger not firing with insert - sql

Question

DROP TABLE ENROLLMENT CASCADE CONSTRAINTS;
DROP TABLE SECTION CASCADE CONSTRAINTS;
CREATE TABLE SECTION
(
SectionID CHAR(5),
Course VARCHAR2(7),
Students NUMBER(2,0) DEFAULT 0,
CONSTRAINT PK_SECTION
PRIMARY KEY (SectionID)
);
CREATE TABLE ENROLLMENT
(
SectionID CHAR(5),
StudentID CHAR(7),
CONSTRAINT PK_ENROLLMENT
PRIMARY KEY (SectionID, StudentID),
CONSTRAINT FK_ENROLLMENT_SECTION
FOREIGN KEY (SectionID)
REFERENCES SECTION (SectionID)
);
INSERT INTO SECTION (SectionID, Course) VALUES ( '12345', 'CSC 355' );
INSERT INTO SECTION (SectionID, Course) VALUES ( '22109', 'CSC 309' );
INSERT INTO SECTION (SectionID, Course) VALUES ( '99113', 'CSC 300' );
INSERT INTO SECTION (SectionID, Course) VALUES ( '99114', 'CSC 300' );
SELECT * FROM SECTION;
COMMIT;
CREATE TRIGGER AddStudent AFTER INSERT ON ENROLLMENT
BEGIN
DBMS_OUTPUT.PUT_LINE('DONE');
END;
All I am trying to see is if the trigger is fired and when I run a script like INSERT INTO enrollment VALUES('12345','1234567');
I have no output, just "1 row inserted" but I do not get "done" making me thing the trigger is not fired.

Answer 1

The only observable effect of your insert trigger is this:
DBMS_OUTPUT.PUT_LINE('DONE');
This just puts a message into the debug buffer. To see the result, you need to enable DBMS Output.
You can do this in SQL Developer via the View menu, choose Dbms Output, and click the green "+" button. Then run your code and you should see the output, if any.
If you use SQL*Plus instead, you would run SET SERVEROUT ON.