SQL Server Trigger INSTEAD OF INSERT to Set Timestamps Before Commit - sql

Question

In SQL Server 2008 R2, I am looking to create a trigger that imitates the behavior of an Oracle BEFORE INSERT trigger, where any insert that comes in has the trigger update the UPDATE_TS and CREATE_TS to the current timestamp right before the persist.
To issue I am seeing right now is the error:
An explicit value for the identity column in table 'MY_TABLE' can only be specified when a column list is used and IDENTITY_INSERT is ON
I am not sure if it is a good idea to turn SET IDENTITY INSERT table ON and then
SET IDENTITY INSERT table OFF within the trigger. Maybe that is a possible solution.
Please advise on best practice.
Example Table is called MY_TABLE:
CREATE TABLE [myschema].[MY_TABLE](
[MY_TABLE_ID] [bigint] IDENTITY(1,1) NOT NULL,
[FIELD_TO_UPDATE] [varchar](255) NOT NULL,
[CREATE_TS] [datetime] NULL,
[UPDATE_TS] [datetime] NULL),
PRIMARY KEY (MY_TABLE_ID))
Trigger:
CREATE TRIGGER my_table_create_ts_trigger
ON [mydb].myschema.MY_TABLE
INSTEAD OF INSERT
AS
BEGIN
INSERT INTO MY_TABLE([MY_TABLE_ID], [FIELD_TO_UPDATE], [CREATE_TS], [UPDATE_TS])
SELECT i.MY_TABLE_ID, i.FIELD_TO_UPDATE, GETDATE(), GETDATE()
FROM INSERTED as i
END

Answer 1

Not sure why you are using dynamic SQL, it's not really needed. Also, no need to do an UPDATE afterwards, you can just do:
CREATE TRIGGER my_table_create_ts_trigger
ON [mydb].myschema.MY_TABLE
INSTEAD OF INSERT
AS
BEGIN
INSERT INTO MY_TABLE(<list of every non identity column here>)
SELECT <list of every non identity column and the date here>, GETDATE()
FROM INSERTED
END
Also, you should list the columns explicitely in the INSERT and the SELECT.

Answer 2

I must be a glutton for punishment, but I have a better suggestion. Drop the trigger.
Change your table to:
CREATE TABLE [myschema].[MY_TABLE](
[MY_TABLE_ID] [bigint] IDENTITY(1,1) NOT NULL,
[FIELD_TO_UPDATE] [varchar](255) NOT NULL,
-- change this column to have a default:
[CREATE_TS] [datetime] NOT NULL DEFAULT CURRENT_TIMESTAMP,
-- and this column too, I guess:
[UPDATE_TS] [datetime] NOT NULL DEFAULT CURRENT_TIMESTAMP),
PRIMARY KEY (MY_TABLE_ID))
Why would you allow those columns to be NULL? Why do you want to use an elaborate trigger to replace something that is much simpler to implement with a default constraint?
You don't need the trigger, and I don't understand what benefit it brings or why you want to replicate a BEFORE trigger. An INSTEAD OF trigger is similar, but not exactly the same thing.