SELECT  stat_day, obs_day, stat_week, obs_week, NULL AS stat_cputotal,  
        stat_memfree, stat_md5, stat_month, obs_month, stat_type,       
        stat_memused, stat_10min, obs_10min, NULL AS stat_cpusystem,    
        stat_epoch, obs_epoch, stat_30day, obs_30day, stat_idx, obs_idx,
        NULL AS stat_cpuidle, stat_memtotal, stat_qtr, obs_qtr,         
        NULL AS stat_cpuuser, stat_hour, obs_hour, obs_10min, stat_10min,
        obs_30day, stat_30day, obs_day, stat_day, obs_epoch, stat_epoch,
        obs_hour, stat_hour, obs_idx, stat_idx, obs_month, stat_month,  
        obs_qtr, stat_qtr, obs_week, stat_week, serial_num,             
        NULL AS dputil_cpuid, NULL AS wms_pk                            
FROM ((      
    SELECT  stat_qtr, obs_qtr, stat_qtr AS cus_qtr, stat_qtr AS crash_qtr,
            stat_qtr AS evt_qtr, stat_30day, obs_30day, stat_30day AS cus_30day,  
            stat_30day AS crash_30day, stat_30day AS evt_30day, stat_month,
            obs_month, stat_month AS cus_month, stat_month AS crash_month,
            stat_month AS evt_month, stat_week, obs_week, stat_week AS cus_week,  
            stat_week AS crash_week, stat_week AS evt_week, stat_day, obs_day,
            stat_day AS cus_day, stat_day AS crash_day, stat_day AS evt_day,
            stat_hour, obs_hour, stat_hour AS cus_hour, stat_hour AS crash_hour,  
            stat_hour AS evt_hour, stat_10min, obs_10min, stat_10min AS cus_10min,
            stat_10min AS crash_10min, stat_10min AS evt_10min, stat_epoch,
            obs_epoch, stat_epoch AS cus_epoch, stat_epoch AS crash_epoch,
            stat_epoch AS evt_epoch, stat_idx, obs_idx, stat_idx AS cus_idx,
            stat_idx AS crash_idx, stat_idx AS evt_idx, obs_10min, obs_30day,
            obs_day, obs_epoch, obs_hour, obs_idx, obs_month, obs_qtr, obs_week,  
            serial_num, stat_md5, MIN(stat_memfree) AS stat_memfree,    
            MIN(stat_md5) AS stat_md5, MIN(stat_type) AS stat_type,     
            MIN(stat_memused) AS stat_memused, MIN(stat_memtotal) AS stat_memtotal
    FROM (   
        select * from (mem_stat NATURAL LEFT OUTER JOIN host )          
    )        
    GROUP BY stat_qtr, stat_30day, stat_month, stat_week, stat_day, stat_hour,
             stat_10min, stat_epoch, stat_idx, obs_10min, obs_30day, obs_day,
             obs_epoch, obs_hour, obs_idx, obs_month, obs_qtr, obs_week,
             serial_num, stat_md5
))

##</code><code>##

SELECT  stat_qtr, obs_qtr, stat_qtr AS cus_qtr, stat_qtr AS crash_qtr,
        MIN(stat_memfree) AS stat_memfree
FROM (   
    <<<previous statement after it works>>> 
)        

##</code><code>##

<<<previous statement after it works>>>
GROUP BY stat_qtr