Make SSN Field Mandatory

Content

Hello,

We are trying to make SSN field mandatory while hiring(through UI or HDL). Also, we need to set up a validation to make sure the SSN values are duplicated across employee records.

1) While hiring an employee, SSN should not be blank, it should throw an error and should not allow to proceed further.
2) While hiring an employee, system should throw an error if the SSN is a duplicate of an existing employee or ex-employee.
3) While hiring an employee, system should throw an error if the SSN is updated at a later point, and the new SSN is a duplicate of another employee or ex-employee.