I have two lists:
List A - a workflow tasks list
List B - an employees list containing fields such as employee name (person column), employee number (single line of text), etc.
I have a workflow that assigns tasks to a user on List A. As part of completing the task, the user is required to enter an employee number which is then copied by the workflow to the employee list (List B).
How can I ensure that the employee number entered when the task is completed does not already exist in List B. The same requirement applies to the employee name field which is a person column. How can I ensure that when the user clicks to complete the task, that the data entered does not already exist in the employees list.
I have thought of doing the check on the workflow after the task is completed and then reassign another task if the value already exists, but I think it will be better if the check is done on submit of the task.
Thanks in advance.