SELECT   DECODE (state,
                 0, 'FREE',
                 1, DECODE (lrba_seq, 0, 'AVAILABLE', 'BEING USED'),
                 3, 'BEING USED',
                 state
                ) "BLOCK STATUS",
         COUNT (*)
    FROM x$bh
GROUP BY DECODE (state,
                 0, 'FREE',
                 1, DECODE (lrba_seq, 0, 'AVAILABLE', 'BEING USED'),
                 3, 'BEING USED',
                 state
                );