SELECT ORG_ID,CUST_NUM,TRANS_TYPE,TRANSACTION_DATE,QUANTITY,
TTL_QTY=(SELECT SUM(CASE WHEN B.TRANS_TYPE='REC' THEN -B.QUANTITY ELSE B.QUANTITY END) FROM TABLE B
WHERE B.ORG_ID=A.ORG_ID AND B.CUST_NUM=A.CUST_NUM AND B.TRANSACTION_DATE<=A.TRANSACTION_DATE)
FROM TABLE A