JAVA J2EE 4 U

 SELECT 

    d.name AS db_name,

    ROUND(AVG((bs.completion_time - bs.start_time) * 1440), 2) AS avg_full_backup_duration_mins

FROM 

    rc_backup_set bs

JOIN 

    rc_database d ON bs.db_key = d.db_key

WHERE 

    bs.backup_type = 'D'  -- Full backup

    AND bs.start_time IS NOT NULL

    AND bs.completion_time IS NOT NULL

    AND bs.start_time >= SYSDATE - 30

    AND bs.status = 'A'  -- Available

GROUP BY 

    d.name;