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

Create a non-computed column of appropriate datatype. Create an Insert trigger (and an Update trigger if data will change). You can then persist the function output in a column.

ALTER TABLE SomeTable ADD FormattedSSN VARCHAR(11)
GO

CREATE TRIGGER dbo.TR_I_SomeTable ON  dbo.SomeTable AFTER INSERT
AS 
BEGIN
    SET NOCOUNT ON;

    update s
    set s.FormattedSSN = dbo.FormatSSN()
    from SomeTable AS s
        join inserted i on i.id = s.id

END
GO