Example of PL/SQL trigger in Oracle

In the below example line 2 is A triggering event or statement, lines 4-9 are A trigger action.

Example of creating a trigger based on the following two tables:

CREATE TABLE T1 (a INTEGER);
CREATE TABLE T2 (b INTEGER);

We will create a trigger that may insert a tuple into T2 when a tuple is inserted into T1. The trigger checks if the inserted row in T1 is has a value less than 5 only then a tuple is inserted in T2.

1 CREATE TRIGGER tr1
2 AFTER INSERT ON T1
3 REFERENCING NEW AS newRow
4 FOR EACH ROW
5 WHEN (newRow.a <= 5)
6 BEGIN
7 INSERT INTO T2
VALUES(:newRow.a);
8 END tr1;
9 .
10 run;