How to validate that only one check box is checked in detail block

Question

Hi All,
I am using oracle Forms 10G on windows.
I need help on how to validate that only one check box is checked in detail block. I have multiple records in the detail block and I have check boxes for each record in the detail block.
I have a button to select the values from the detail records where the check box is checked. But I want to make sure that only one record is check not more than one.
How do I validate this on a push button trigger?
Thanks

Answer 1

When I've done this kind of thing, I create a Form level variable of TYPE number and then add or subtract to this variable as I check and uncheck the checkboxes. If the value of the variable is 1, then you know that only one checkbox is selected. If the value is greater than 1, then you know the user has selected more than one check box. You could also add code to your When-Checkbox-Changed trigger to test the variable and instruct the user to un-check selected record before selecing a new record.
With respect to the Form level variable, you can use a GLOBAL, PARAMETER or Program Unit package specification. I prefer to use the PU Package Spec as this method has a smaller memory footprint. For example, in the Program Unit node of the object navigator create the following;
/* Form variables package spec */
PACKAGE Form_Vars IS
  CheckBox_Cnt     NUMBER := 0;
END;Now in your When-Checkbox-Changed trigger...
BEGIN
   IF ( Form_Vars.CheckBox_Cnt = 0 ) THEN
      Form_Vars.CheckBox_Cnt  := Form_Vars.CheckBox_Cnt  + 1;
   ELSE
      /* it's assumed the value is greater than 0 */
      Message('Please uncheck selec ted record before choosing a new record.');
      RAISE Form_Trigger_Failure;
   END IF;
END;Hope this helps,
Craig B-)
If someone's response is helpful or correct, please mark it accordingly.
Edited by: CraigB on Feb 3, 2011 10:15 AM