Triggers Wizard (DB2 Z/OS)
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A trigger defines a set of actions that take place in conjunction with, or are triggered, for a particular base table, with an insert, update, or delete statement. Triggers are good ways to validate input data, read from other tables for cross-referencing purposes, and other similar purposes. The Trigger wizard lets you create a trigger without requiring you to know any of the underlying commands.
To create a new trigger using a wizard
- Open a creation wizard for a trigger. For details, see Opening an Object Wizard.
- Use the following topics as a guide to setting properties and performing tasks as you pass through the wizard panels:
- Properties panel. For details, see Triggers (DB2 z/OS) - Properties.
- Column Selection panel. For details, see Triggers (DB2 z/OS) - Column Selection.
- Definition panel. For details, see Triggers (DB2 z/OS) - Definition.
- Click Execute to create the object.
Triggers (DB2 z/OS) - Properties
When creating or editing a trigger, this tab/panel lets you work with the following settings:
| Setting | Description |
|---|---|
|
Table Schema and Table Name |
Choose the owner and name of the table for which you are creating the trigger. |
|
Schema and Name |
Choose the owner and name of the trigger you are creating. |
|
Trigger Timing |
BEFORE. BEFORE triggers serve as extensions to the constraint subsystem and are most often used to validate input data, generate values for newly-inserted rows, and read from other tables for cross-reference purposes.
AFTER. AFTER triggers are run after the integrity constraint validations. You can use them to modify operations in the database or be used for activities beyond the database, like supporting an alert notification. |
|
Trigger Events |
You must associate INSERT triggers with INSERT statements. For example, if a data load operation doesn't include an INSERT statement, the trigger is not invoked. You can associate an UPDATE trigger with specific columns of the base table and are activated only when those columns are updated. |
|
Trigger Type |
STATEMENT. (Triggers only once.) ROW. (Triggers for each affected row.) ROW triggers run as many times as there are rows in the affected section. If the set of affected rows is empty, the trigger doesn't run. |
|
Old Table Alias |
Type the name of a temporary table of rows as they exist before they're updated or deleted. |
|
New Table Alias |
Type a name for a temporary table of rows as they exist after they're updates or inserted. |
|
Old Row Alias |
Type a name for the rows as they are before they're updated or deleted. |
|
New Row Alias |
Type a name for the rows as they are after they're updated or inserted. |
Triggers (DB2 z/OS) - Column Selection
If you chose UPDATE as the Trigger Event, select the columns, and then select the check box beside each column that is to fire the trigger.
Triggers (DB2 z/OS) - Definition
Complete the CREATE TRIGGER outline provided by typing or pasting the body of the trigger.