/*
** Built-in: DEFAULT_VALUE 
** Example: Make sure a Global variable is defined by 
** assigning some value to it with Default_Value 
*/ 
BEGIN 
/* 
** Default the value of GLOBAL.Command_Indicator if it is 
** NULL or does not exist. 
*/ 
  Default_Value('***','global.command_indicator'); 
/* 
** If the global variable equals the string we defaulted 
** it to above, then it must have not existed before 
*/ 
  IF :Global.Command_Indicator = '***' 
  THEN Message('You must call this screen from the Main Menu'); 
    RAISE Form_Trigger_Failure; 
  END IF; 
END; 

/* Example 2:
** Call a form, pass a parameter list (if it exists)
*/
DECLARE
  pl_id        PARAMLIST;
  theformname  VARCHAR2(20);
BEGIN
  theformname := 'addcust';

 /* Try to lookup the 'TEMPDATA' parameter list */
   pl_id := GET_PARAMETER_LIST('tempdata');
  IF ID_NULL(pl_id) THEN
    CALL_FORM(theformname);
  ELSE
    CALL_FORM(theformname,
              hide,
              no_replace,
              no_query_only,
              pl_id);
  END IF;
 
  CALL_FORM('lookcust', no_hide, do_replace, query_only);
END;

/* 
** Built-in: CREATE_PARAMETER_LIST 
** Example: Create a parameter list named 'TEMPDATA'. First 
** make sure the list does not already exist, then 
** attempt to create a new list. Signal an error 
** if the list already exists or if creating the 
** list fails. 
*/ 
DECLARE 
  pl_id ParamList; pl_name VARCHAR2(10) := 'tempdata'; 
BEGIN 
  pl_id := Get_Parameter_List(pl_name); 
  
  IF Id_Null(pl_id) 
  THEN 
    pl_id := Create_Parameter_List(pl_name); 
    
    IF Id_Null(pl_id) 
    THEN 
      Message('Error creating parameter list '||pl_name); 
      RAISE Form_Trigger_Failure; 
    END IF; 
  ELSE 
    Message('Parameter list '||pl_name||' already exists!'); 
    RAISE Form_Trigger_Failure; 
  END IF; 
END;