SELECT
    EMP_CODE AS CODE
    , EMP_LAST_NAME AS SURNAME
    , EMP_FIRST_NAME AS NAME
FROM
(
SELECT
 EMP_CODE,
 EMP_LAST_NAME,
 EMP_FIRST_NAME,
--社員姓、社員名に半角スペースが含まれている場合は、除去して比較
 trim(replace(EMP_LAST_NAME, ' ',''))||trim(replace(EMP_FIRST_NAME, ' ','')) AS EMP_NAME
FROM
 EMP
WHERE
 VALID_FLG = '1'
)
GROUP BY
 EMP_NAME

ORDER BY
EMP_NAME,
EMP_CODE