There are following two types of triggers:
Database triggers are executed implicitly whenever a Data Manipulation Language (DML) statement is carried out on a database table or a Data Definition Language (DDL) statement, such as CREATE OR ALTER, is performed on the database.
They may also be executed when a user or database event occurs, such as a user logs on or a database is shutdown. Application triggers are executed implicitly whenever a DML event takes place within an application, such as WHEN_NEW_FORM_INSTANCE in the Oracle Forms application.
Database triggers are executed implicitly whenever a Data Manipulation Language (DML) statement is carried out on a database table or a Data Definition Language (DDL) statement, such as CREATE OR ALTER, is performed on the database.
They may also be executed when a user or database event occurs, such as a user logs on or a database is shutdown. Application triggers are executed implicitly whenever a DML event takes place within an application, such as WHEN_NEW_FORM_INSTANCE in the Oracle Forms application.