Calculate Indexes Size via dm_db_index_physical_stats in TSQL

Calculate Indexes Size via dm_db_index_physical_stats
Sometimes we want to calculate how much space do table indexes get. We can
use sp_spaceused system stored procedure to measure how much does
specific object take physical space. In MSSQL 2005 we can also use system
procedure sys.dm_db_index_physical_stats.

"This little snip of code allows you to list how many indexes are present on a table, their type and how big (kb and mb) they are"

SELECT [name]
      ,type_desc
      ,space_used_in_kb = (page_count * 8.0)
      ,space_used_in_mb = (page_count * 8.0 / 1024.0)
  FROM sys.indexes I
  JOIN sys.dm_db_index_physical_stats(db_id()
                                     ,object_id('.')
                                     ,null
                                     ,null
                                     ,null) P
    ON I.[object_id] = P.[object_id]
   AND I.[index_id] = P.[index_id]