How to Create a trigger for a DB2 database

InDB2 databaseOperation, we often useTriggerThis seems a little difficult for beginners. But it doesn't matter. This article introduces some knowledge about DB2 database triggers and provides an instance for creating triggers. For Beginners, if you don't know much about them, you can also directly apply the following instances to create a trigger. Next let's take a look at this part.

Create a trigger that includes the following parts:

Trigger name :......

Trigger trigger event: insert, delete, update

Activation time: before, after

Granularity: for each statement, for each row

Transition variable:

Old row: indicates the modified value before the event is triggered:

New row indicates the value modified after the event is triggered.

Old table indicates a read-only hypothetical table of all modified rows before the event is triggered.

New table indicates a hypothetical table in which all rows are modified after the event is triggered.

Trigger condition: starting from WHEN, it can contain one or more predicates, including transition variables and subqueries.

Trigger body: it consists of one or more SQL statements.

Create an instance of the DB2 trigger:

 
 

  
  
CREATE TRIGGER REORDER  
  
  
 
  
  
AFTER UPDATE OF ON_HAND, MAX_STOCKED ON PARTS  
  
  
 
  
  
REFERENCING NEW AS N_ROW  
  
  
 
  
  
FOR EACH ROW MODE DB2SQL  
  
  
 
  
  
WHEN (N_ROW.ON_HAND < 0.10 * N_ROW.MAX_STOCKED  
  
  
 
  
  
AND N_ROW.ORDER_PENDING = 'N')  
  
  
 
  
  
BEGIN ATOMIC  
  
  
 
  
  
VALUES(ISSUE_SHIP_REQUEST(N_ROW.MAX_STOCKED -  
  
  
 
  
  
N_ROW.ON_HAND,  
  
  
 
  
  
N_ROW.PARTNO));  
  
  
 
  
  
UPDATE PARTS SET PARTS.ORDER_PENDING = 'Y' 
  
  
 
  
  
WHERE PARTS.PARTNO = N_ROW.PARTNO;  
  
  
 
  
  
END 
 
 

The introduction of the DB2 database trigger is here. I hope this introduction will be helpful to you.