I have hte following command:
SELECT 'ISIT' as TYPE, ISIT_ISSUE_DATE, ISIT_ITEM, ISIT_ISSUE, ISIT_QUANTITY, ISIT_VALUE
FROM ISSUE_ITEM
UNION
SELECT 'RCIT' as TYPE, RCIT_LAST_UPDATE, RCIT_ITEM, RCIT_RECEIPT, RCIT_QUANTITY, RCIT_VALUE
FROM RECEIPT_ITEM
ORDER BY ISIT_ISSUE_DATE
that is working...