2 13 Triggers

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2.13 Triggers

This display results when:

An existing trigger has been chosen for review.

A new trigger is to be added

DC@P700103 Define / Change a Trigger

File : XXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Field : XXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Order to process / source . . . . . 999 / DATA DICTIONARY

User description of trigger . . . . _________________________

Trigger Function Name . . . . . . . _______

Before After

Trigger Point(s) . . . . . . . . . . Open _ _

Close _ _

Read _ _

Insert _ _

Update _ _

Delete _ _

And/Or Field Op Field/Literal

Trigger When . . . . . _______ ___ ____________________

___ _______ ___ ____________________ +

Fnn=Help Fnn=Exit Fnn=Cancel Fnn=Messages

Note that file name is only displayed when working at file level. Change and Delete command keys are only enabled when displaying an existing check.

If an existing trigger is being reviewed then the CHANGE key can be used to place the screen in change mode and the required changes made.

If an existing trigger is being reviewed then the DELETE key can be used to delete the trigger. Note that the delete is immediate. No confirmation is required.

If a new trigger is being added then the screen will be presented initially with default values. Change as required and press Enter to complete specification of the trigger.

Input Options

These input options apply to a trigger:

Order to Process

Mandatory, but always prefilled to <highest order number + 10>. Triggers are performed (and displayed) in the sequence of these order numbers (within the trigger level). Order numbers must be unique within the trigger level.

For instance:

Trigger	Level	Order To Process
TRIG01	Dictionary	100
TRIG02	Dictionary	200
TRIG03	File	20
TRIG04	Dictionary	50
TRIG05	File	10

would be performed: TRIG04, TRIG01, TRIG02, TRIG05, TRIG03.

Source

Output field. Indicates the source or level at which the trigger applies.

User Description of Trigger

Mandatory. Enter a brief description of the trigger to aid other users in understanding its purpose.

Trigger Function Name

Mandatory. Enter the name of the trigger function which will be called when the trigger conditions are satisfied. The named function must be defined with the TRIGGER parameter on the FUNCTION command. (Refer to the FUNCTION command in the Technical Reference Guide for details).

Trigger Points

At least one point where the function is to be triggered must be entered (by entering a "Y" at the required point).

Trigger When

Optional. If no test conditions are specified the trigger will be unconditionally invoked.

Rules for entering conditions are as follows:

Operations allowed are:

GT	Greater than
GE	Greater than or equal to
LT	Less than
LE	Less than or equal to
EQ	Equal to
NE	Not equal to
REF	Refers to

All operation codes can be suffixed by a "P" indicating that the previous value of the nominated field should be used. Such conditions are only valid for "Update" operations. Also Part 2 of the condition must not be a literal if this type of operation code is used.

No conditions are allowed if "Open" or "Close" are used.

The "REF" operation code is only valid for "Insert", "Update" and "Read" operations.

If the trigger is defined at dictionary level, the conditions can only involve the field to which the trigger is being linked.

If the trigger is defined at the file level, the conditions can involve any other real or virtual fields in the file to which the trigger is being linked.

Examples

Trigger field:

Name	Type	Len	Dec
SALARY	P	12	2

Trigger function:

Name	Function	Trigger Before	Points After	Comments
TRGFN1	Open			Call trigger function TRGFN1 following an insert or update of field SALARY, or before a delete of field SALARY. Note that no conditions have been applied to this trigger.
	Close
	Read
	Insert		Y
	Update		Y
	Delete	Y

Refer to Trigger Functions for full details and examples

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