SQL Server Get Datasize of Table

DataSize.sql

if object_id('dbo.DataSize', 'FN') is not null
begin
	drop function dbo.DataSize	
end
go
create function dbo.DataSize(@object_id int)
returns float
as
begin
	declare @PageSize float
	select  @PageSize = v.low/1024.0 from master.dbo.spt_values v where v.number=1 and v.type=N'E'

	declare @DataSize float
	select  @DataSize = case
        when (tbl.is_memory_optimized=0) then
        isnull((select @PageSize * sum(case when a.type <> 1 then a.used_pages when p.index_id < 2 then a.data_pages else 0 end)
        from sys.indexes as i
        join sys.partitions as p on p.object_id = i.object_id and p.index_id = i.index_id
        join sys.allocation_units as a on a.container_id = p.partition_id
        where i.object_id = tbl.object_id),0.0)
        else
        isnull((select (tms.[memory_used_by_table_kb])
		from [sys].[dm_db_xtp_table_memory_stats] tms
		where tms.object_id = tbl.object_id), 0.0)
        end
	from  sys.tables AS tbl
	where tbl.object_id = @object_id
	return	@DataSize
end
go