SELECT

DP.DEPT_CODE,
DP.DEPT_NAME,
OD.ORDER_NO,
CU.CUST_CODE,
CU.CUST_NAME,
OD.ORDER_AMT

FROM TBL_ORDERS AS OD

INNER JOIN TBL_DEPT AS DP
ON DP.DEPT_CODE = OD.DEPT_CODE

LEFT OUTER JOIN TBL_CUST AS CU
ON CU.CUST_CODE = OD.CUST_CODE

ORDER BY OD.DEPT_CODE,
OD.ORDER_NO;