Examples of how Triggers Might be Used

Example 1: Calculates the current balance of the account:

     Object           : Account (ACNT) 
     Trigger Field    : "Account Balance" (ACCBAL)
     Trigger Method   : Calculates the current balance of the account.
     Trigger Event(s) : 1. AFTER READ when ACCBAL is REF (referenced)
 
     Invoked By       : (i.e. How is an account balance retrieved ?)
                         FETCH FIELDS(....#ACCBAL....) 
                               FROM_FILE(ACNT)
                     or SELECT FIELDS(....#ACCBAL....) 
                               FROM_FILE(ACNT)
     Comments         : Quite efficient because ACCBAL is only 
                        calculated when the requester asks for it.

Example 2: Submits batch order print job:

     Object           : Order (ORDR) 
     Trigger Field    : "Print Required" (PRINT_REQ)
     Trigger Method   : Submits batch order print job. Batch function
                        prints order and updates PRINT_REQ to 'N'.
     Trigger Event(s) : 1. AFTER INSERT when PRINT_REQ EQ  'Y'
                        2. AFTER UPDATE when PRINT_REQ EQ  'Y'
                                        and  PRINT_REQ NEP PRINT_REQ
 
     Invoked By       : (i.e. How is an order submitted for printing ?)
                         CHANGE #PRINT_REQ 'Y'
                         UPDATE FIELD(#PRINT_REQ) IN_FILE(ORDR)
 
     Comments         : It may seem a little obscure as an IBM i 
                        based trigger but what if the update 
                        comes from a PC based application via 
                        the LCOE facility, or from a batch job 
                        that starts automatically every morning 
                        and automatically selects certain
                        orders for printing ?