• The "BEFORE" triggers:
  A "BEFORE" trigger is called:
  • before running an HFSQL function (HAdd, HModify, HDelete, ...).
  • before running a function for managing the Table controls based on a data file.
    A "BEFORE" trigger can be used for example to check the consistency of data for the items of a record. With this type of trigger, an HFSQL variable can be initialized in order to cancel the execution of the associated HFSQL function.
• The "AFTER" triggers:
  An "AFTER" trigger is called:
  • after running an HFSQL function (except if the program was interrupted during the execution of this function).
  • after running a function for managing the Table controls based on a data file.
    An "AFTER" trigger can be used to manage the process of errors for example.

• Several server triggers can be associated with the same data file.
• The triggers being defined on the server, they are taken into account regardless of the client application run. Any new trigger defined on the server is automatically taken into account.
• The server triggers are run:
  • by HAdd, HDelete, HModify, HWrite, HCross.
  • by TableAdd, TableAddLine, TableDelete, TableModify that implicitly use the HFSQL functions.
  • by the INSERT queries (HAdd trigger), UPDATE queries (HModify trigger) and Delete queries (HDelete trigger).

Prerequisite

• on the "Analysis" tab, in the "Creation" group, expand "New" and select "Trigger".
• select "New trigger" in the context menu of the dockable "Analysis" pane.
• display the "HF triggers" tab of the data file description window and click "Create a new trigger"

• in the "General" tab:
  
  • the name of the trigger.
  • the stored WLanguage procedure that is associated with the trigger.
  • the mode for releasing the trigger (BEFORE or AFTER the execution of the HFSQL functions).
  • the HFSQL functions that will release the trigger.
• in the "General" tab:
  
  • the data files associated with the trigger.

• in the analysis pane.
• directly in the analysis graph: if a server trigger is associated with a data file, a specific icon appears: .

Taking the server triggers into account

• when creating the data files (HCreation or HCreationIfNotFound).
• with the HCreateServerTrigger function. In this case, the corresponding stored procedure must also be updated by HUpdateSet.
• during the automatic modification of the data files if necessary.

Stored procedures linked to a trigger

A trigger procedure (or stored procedure) receives no parameters. However, some HFSQL state variables are positioned before each call:

H.FileName	Character string: Logical name of the data file for which the trigger is activated. Warning Depending on the logical name used by the application, the value of the variable H.FileName variable may be different (using aliases, for example). It is recommended to use: MyFile.DescribedName to find out the logical name of the data file being manipulated (without taking aliases into account). MyFile.PhysicalName to find out the physical name of the data file being handled.
H.Action	Character initialized to "A" for a Before trigger and to "P" for an After trigger.
H.TriggerFunction	String: Name of the HFSQL function that triggered the trigger. Warning The variable H.FunctionTrigger variable is deprecated in favour of the H.FunctionTriggerNumber. The information given by the variable is independent of the language used to run the application.
New in version 2025 H.TriggerFunctionNumber	Constant used to identify the function that triggered the trigger: htrgHAjoute The function that triggered the trigger is HAdd. htrgHEcrit The function that triggered the trigger is HWrite. htrgHModifies The function that triggered the trigger is HModify. htrgHRaye The function that triggered the trigger is HCross. htrgHSuppresses The function that triggered the trigger is HDelete.
H.ToDo	During the execution of a before trigger: cancelling the execution of the current HFSQL function by assigning "A" to the HFSQL state variable: H.ToDo = "A". In this case, the action is not performed and the function (HAdd, HModify, etc.) returns True (no error). cancelling the execution of the ongoing HFSQL function by assigning "E" to the HFSQL state variable: H.AFaire = "E". In this case, the action is not performed and the function (HAdd, HModify, etc.) returns False. The error message reads: "Action on data file XXX has been interrupted by the trigger".

Note In the case where a "BEFORE" and an "AFTER" trigger are associated with an HFSQL function, if the "BEFORE" trigger cancels the execution of the HFSQL function (by setting H.AFaire to "A"), the "AFTER" trigger is not triggered.

Testing a stored procedure called by a trigger

1. In the analysis pane, select the stored procedure whose test must be run.
2. Select "Test procedure" in the context menu of the stored procedure.
3. The window for entering the parameters of the procedure is displayed. In this window, you can:
   • Type the procedure parameters.
   • Run the procedure test.
     Note: this window can be used to restart the run several times by modifying the parameters.
4. When the procedure test is run:
   • An update of the stored procedure is proposed if necessary.
   • The procedure is started on the server.
   • The return value of procedure is displayed if necessary.

• The debugging port is port 27281 by default. This port must be opened in the firewall. This port can be modified in the HFConf.ini file.
• To test a stored procedure, you must have debugging rights on the database.
• The traces used in the stored procedures are displayed in the debugger trace pane.
• The code of the stored procedure may contain breakpoints: the debugger will then be launched.
• The elements deployed on the server are used during the test.
• InTestMode returns True.

The WLanguage functions