Downtime Query for Oracle Production Scheduling

SELECT org.organization_code organization_code,
    crd.resources resources,
    crm.resource_desc resource_description,
    TO_CHAR(grum.from_date, 'DD-MON-YYYY HH24:MI:SS') start_time,
    TO_CHAR(grum.to_date, 'DD-MON-YYYY HH24:MI:SS') stop_time,
    floor(((grum.to_date-grum.from_date)*24*60*60)/3600) || ':' || ROUND((((grum.to_date-grum.from_date)*24*60*60) -     floor(((grum.to_date-grum .from_date)*24*60*60)/3600)*3600)/60) || ':' || ROUND((((grum.to_date-grum.from_date)    *24*60*60) - floor(((grum.to_date-grum .from_date)*24*60*60)/3600)*3600 - (ROUND((((grum.to_date-    grum.from_date)*24*60* 60) - floor(((grum.to_date-grum.from_date)*24*60*60)/3600)*3600)/60)*60) ))
    elapsed_time,
    grum.reason_code reason_code,
    mtr.description reason_description
FROM     org_organization_definitions org,
    cr_rsrc_dtl crd,
    CR_RSRC_MST crm,
    gmp_rsrc_unavail_man grum,
    MTL_TRANSACTION_REASONS mtr
WHERE org.organization_id = crd.organization_id
    --AND org.organization_code = NVL(:ORG_CODE,org.organization_code)
    AND crd.resource_id = grum.resource_id
    AND crd.resources = crm.resources
    --AND crd.resources = NVL(:RESOURCES,crd.resources)
    AND grum.reason_code = mtr.reason_name(+)
    --AND grum.reason_code = NVL(:REASON_CODE,grum.reason_code)
    AND (TO_CHAR(grum.from_date,'YYYY/MM/DD') >= '2012/02/22'
    AND TO_CHAR(grum.to_date,'YYYY/MM/DD') <= '2012/02/22')
     -- and (grum.to_date >= '0-jan-12' and grum.to_date <'04-jan-12')
    -- AND to_char(nvl(grum.from_date,SYSDATE),'YYYY/MM/DD HH24:MI:SS') between nv l    (:START_FROM_DATE,to_char(nvl(grum.from_date,SYSDATE),'YYYY/MM/DD HH24:MI:SS'))
    AND nvl(:START_TO_DATE,to_char(nvl(grum.from_date,SYSDATE),'YYYY/MM/DD HH24:MI: SS'))
    -- AND to_char(nvl(grum.to_date,SYSDATE),'YYYY/MM/DD HH24:MI:SS')
    between nvl (:STOP_FROM_DATE,to_char(nvl(grum.to_date,SYSDATE),'YYYY/MM/DD HH24:MI:SS'))
    AND nvl(:STOP_TO_DATE,to_char(nvl(grum.to_date,SYSDATE),'YYYY/MM/DD HH24:MI:SS'))
ORDER BY org.organization_code, crd.resources, grum.from_date