>> How can we make the above code to apply one for a particular user?
This should do:
USE MyDatabase
IF EXISTS (SELECT * FROM sys.triggers
WHERE parent_class = 0 AND name = 'safety')
DROP TRIGGER safety
ON DATABASE
GO
CREATE TRIGGER safety
ON DATABASE
FOR CREATE_TABLE
AS
IF ( SELECT suser_name()) = ur_user_name
BEGIN
PRINT 'You cannot add the object!'
ROLLBACK
END
GO
DROP TRIGGER safety
ON DATABASE
GO