Qualcosa del genere:
ALTER TABLE dbo.MyTable
DROP COLUMN OldComputedColumn
ALTER TABLE dbo.MyTable
ADD OldComputedColumn AS OtherColumn + 10
Qualcosa del genere:
ALTER TABLE dbo.MyTable
DROP COLUMN OldComputedColumn
ALTER TABLE dbo.MyTable
ADD OldComputedColumn AS OtherColumn + 10