SELECT
CASE WHEN ITEM.ITEM_CODE isnull
then ITEM_HISTORY.ITEM_CODE
else ITEM.ITEM_CODE
end as CODE,
CASE WHEN ITEM.ITEM_NAME isnull
then ITEM_HISTORY.ITEM_NAME
else ITEM.ITEM_NAME
end as NAME,
CASE WHEN ITEM.USER_UPDATE_DATETIME isnull
then 'DELETED'
when ITEM_HISTORY.USER_UPDATE_DATETIME isnull
then 'ADDED'
else 'UPDATED'
end as COMP_RSLT
FROM 
(ITEM FULL OUTER JOIN ITEM_HISTORY 
ON 
(ITEM.ITEM_CODE = ITEM_HISTORY.ITEM_CODE)) 
as 'UPDATE_COLUMN' 
where ITEM.USER_UPDATE_DATETIME <> ITEM_HISTORY.USER_UPDATE_DATETIME
or ITEM.USER_UPDATE_DATETIME isnull
or ITEM_HISTORY.USER_UPDATE_DATETIME isnull