In some cases, the framework can use only the columns selected in your recordset to identify which record in your table to update.Without all the necessary columns, multiple records might be updated in the table, possibly damaging the referential integrity of the table.
This is done by defining the action, when it will run, and which values the rule updates.
The first setting in a record rule is called an "Action." This defines what Knack will do behind the scenes once the form has been submitted.
When a form is submitted and all the criteria are met, the rule will run.
By default the rule is set to run for every form submission, however, you can add criteria based on one or more specific form values.
Once on the "Record Rules" tab in the view editor, you can select “Add Rule” and you have added your first record rule.