Number of pages in a table

How to find data file pages for a table:

        T.NAME AS table_name,
        P.rows AS no_rows,
        SUM(AU.total_pages) AS total_pages,
        SUM(AU.used_pages) AS used_pages,
        (SUM(AU.total_pages) - SUM(AU.used_pages)) AS unused_pages
        sys.tables T
        INNER JOIN sys.indexes I ON T.OBJECT_ID = I.object_id
        INNER JOIN sys.partitions P ON I.object_id = P.OBJECT_ID AND I.index_id = P.index_id
        INNER JOIN sys.allocation_units AU ON P.partition_id = AU.container_id
GROUP BY, P.rows
ORDER BY total_pages DESC

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