13 Copyright © 2004, Oracle. All rights reserved. Introduction to Triggers

13-2 Copyright © 2004, Oracle. All rights reserved. Objectives After completing this lesson, you should be able to do the following: Define triggers Identify the different trigger categories Plan the type and scope of triggers in a form Describe the properties that affect the behavior of a trigger

13-3 Copyright © 2004, Oracle. All rights reserved. Trigger Overview Event Trigger types Queries Validation Navigation Interaction Internal event Errors/Messages Others PL/SQL Fire PL/SQL Which trigger would you use to perform complex calculations after a user enters data into an item?

13-4 Copyright © 2004, Oracle. All rights reserved. Grouping Triggers into Categories Triggers may be grouped into functional categories: Block processing triggers Interface event triggers Master-detail triggers Message handling triggers Navigational triggers Query-time triggers Transactional triggers Validation triggers Triggers may be grouped into categories based on name: When-Event triggers On-Event triggers Pre-Event triggers Post-Event triggers Key triggers

13-5 Copyright © 2004, Oracle. All rights reserved.

13-6 Copyright © 2004, Oracle. All rights reserved. Defining Trigger Components What event?What action? What level? Type Code Scope

13-7 Copyright © 2004, Oracle. All rights reserved. Trigger Type Pre- Post- When- On- Key- User-named Type Code Scope What event?

13-8 Copyright © 2004, Oracle. All rights reserved. Trigger Type Forms Builder Trigger Types

13-9 Copyright © 2004, Oracle. All rights reserved. Trigger Code Statements PL/SQL User subprograms Built-in subprograms Type Code Scope What action?

13-10 Copyright © 2004, Oracle. All rights reserved. Trigger Scope Levels Form Block Item Code Scope Type What level?

13-11 Copyright © 2004, Oracle. All rights reserved. Trigger Scope Event Order Date

13-12 Copyright © 2004, Oracle. All rights reserved. Specifying Execution Hierarchy Form level Block level Item level On-Message On-Error EH = After EH = Before EH = Override Event

13-13 Copyright © 2004, Oracle. All rights reserved.

13-14 Copyright © 2004, Oracle. All rights reserved. Summary In this lesson, you should have learned that: Triggers are event-activated program units You can categorize triggers based on function or name to help you understand how they work Trigger components are: –Type: Defines the event that fires the trigger –Code: The actions a trigger performs –Scope: Specifies the level (form, block, or item) at which the trigger is defined The Execution Hierarchy trigger property alters the firing sequence of a trigger