How to generate a Guid in SQL Server?

A aspnet role created manually

DECLARE @ID UNIQUEIDENTIFIER
SET @ID = NEWID()

DECLARE @STAMP UNIQUEIDENTIFIER
SET @STAMP = NEWID()

INSERT INTO [dbo].[AspNetRoles]
           ([Id]
           ,[Name]
           ,[NormalizedName]
           ,[ConcurrencyStamp])
     VALUES
           (@ID
           ,'Admin'
           ,'ADMIN'
           ,@STAMP)

This will generate a Guid in SQL Server:

SELECT NEWID()