2 13 Triggers

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