Question

How can I control that only specific columns of a table will be updated?

My method is : create instead of update trigger for these tables and control for update only updatable columns and if updated, non updatable column raise error with an appropriate message.

Answer 1

Yes you can use triggers to achieve that but don’t use INSTEAD OF trigger.
You can better use FOR UPDATE triggers because you don’t have to rewrite the whole update query. You only want to deny not allowed updates. If an action is allowed you don’t throw an error so the data will be updates as usual.

Example:

CREATE TRIGGER [dbo].[CheckUpdate] ON [dbo].[MyTable] FOR UPDATE AS

DECLARE @EXPECTED INT = (SELECT COUNT(0) FROM INSERTED)
DECLARE @ALLOWED INT = (
   SELECT COUNT(0)
   FROM INSERTED i 
   INNER JOIN DELETED d 
   ON i.Id = d.Id
   WHERE i.Name = d.Name -- The readonly column
) 

IF(@EXPECTED <> @ALLOWED) -- True if there are not allowed records to updated
BEGIN
    -- Prevent the record will be updated
    RAISERROR ('Readonly columns cannot be changed',11, 1);
    ROLLBACK
END
--Do nothing in the ELSE because everything seems to be OK
--(the record will be updated)

You also can make use of Stored Procedures to control the update of certain tables.