Computed Column cannot be Persisted

Question

I have a custom function, and I am trying to created a persisted column using this function.

It is giving me following error.

Computed column

Answer 1

How about specifying the definition directly:

ALTER TABLE SomeTable
ADD FormattedSSN as
    case when len(EmployeeSSN) = 9 then
            substring(EmployeeSSN, 1, 3) + '-' +
            substring(EmployeeSSN, 4, 2) + '-' +
            substring(EmployeeSSN, 6, 4)
    else EmployeeSSN end
PERSISTED