Question

I am adding a new GUID/Uniqueidentifier column to my table.

ALTER TABLE table_name
ADD VersionNumber UNIQUEIDENTIFIER UNIQUE NOT NULL DEFAULT NEWSEQUENTIALID()
GO

And when ever a record is updated in the table, I would want to update this column “VersionNumber”. So I create a new trigger

CREATE TRIGGER [DBO].[TR_TABLE_NAMWE]
ON [DBO].[TABLE_NAME]
AFTER UPDATE
AS 
BEGIN 
    UPDATE TABLE_NAME
    SET VERSIONNUMBER=NEWSEQUENTIALID()
    FROM TABLE_NAME D
    JOIN INSERTED I ON D.ID=I.ID/* some ID which is used to join*/
END
GO

But just realized that NEWSEQUENTIALID() can only be used with CREATE TABLE or ALTER TABLE. I got this error

The newsequentialid() built-in function can only be used in a DEFAULT expression for a column of type 'uniqueidentifier' in a CREATE TABLE or ALTER TABLE statement. It cannot be combined with other operators to form a complex scalar expression.

Is there a workaround for this ?

Edit1: Changing NEWSEQUENTIALID() to NEWID() in the trigger solves this, but I am indexing this column and using NEWID() would be sub-optimal

Answer 1

As you say its only available under certain conditions, you could do something nasty like:

DECLARE @T TABLE (G UNIQUEIDENTIFIER DEFAULT NEWSEQUENTIALID())
INSERT @T OUTPUT INSERTED.G VALUES (DEFAULT) 

Does it have to be a GUID? if you use a rowversion you get the same functionality without needing a trigger as well as better indexing performance.