SELECT D.DEPT_CODE,
       D.DEPT_NAME,
       O.ORDER_NO,
       C.CUST_CODE,
       C.CUST_NAME,
       O.ORDER_AMT
  FROM TBL_ORDERS O
 INNER JOIN TBL_DEPT D
    ON O.DEPT_CODE = D.DEPT_CODE
  LEFT JOIN TBL_CUST C
    ON O.CUST_CODE = C.CUST_CODE
 ORDER BY D.DEPT_CODE,
          O.ORDER_NO