sys.dm_db_index_physical_stats

Returns size and fragmentation information for the data and indexes of the specified table or view. For an index, one row is returned for each level of the B-tree in each partition. For a heap, one row is returned for the IN_ROW_DATA allocation unit of each partition. For large object (LOB) data, one row is returned for the LOB_DATA allocation unit of each partition

SELECT * FROM sys.dm_db_index_physical_stats (NULL, NULL, NULL, NULL, NULL);