Create new APPPOOL in sql server

IF NOT EXISTS (SELECT name FROM sys.server_principals WHERE name = 'IIS APPPOOL\MLM')
BEGIN
    CREATE LOGIN [IIS APPPOOL\MLM]
      FROM WINDOWS WITH DEFAULT_DATABASE=[master],
      DEFAULT_LANGUAGE=[us_english]
END
GO
CREATE USER [MLMWebDatabaseUser]
  FOR LOGIN [IIS APPPOOL\MLM]
GO
EXEC sp_addrolemember 'db_owner', 'MLMWebDatabaseUser'
GO