SELECT
CASE WHEN bd.database_id = 32767 THEN 'resourceDb' ELSE db_name(bd.database_id) END AS database_name,
COUNT(*) AS cached_pages_count,
AVG(bd.row_count) AS avg_rows_per_page,
SUM(bd.free_space_in_bytes) AS sum_free_space_in_bytes
FROM
sys.dm_os_buffer_descriptors bd
GROUP BY
bd.database_id
ORDER BY
cached_pages_count DESC