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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 ?