WITH TMP AS (SELECT * FROM EMP E
WHERE E.EMP_CODE NOT IN (SELECT EMP_CODE FROM EMP_INVALID)
UNION ALL
SELECT
    E.EMP_CODE
    , E.EMP_LAST_NAME
    , E.EMP_FIRST_NAME
    , E.EMP_KANA_NAME
    , E.EMP_ENG_NAME
    , E.EMAIL_ACCOUNT
    , E.DEPT_CODE
    , E.VALID_FLG
    , E.UPDATE_USER_NAME
    , E.USER_UPDATE_DATETIME
FROM EMP E
JOIN EMP_INVALID EI
ON E.EMP_CODE = EI.EMP_CODE
WHERE DATETIME(EI.USER_UPDATE_DATETIME) <= DATETIME(E.USER_UPDATE_DATETIME) AND E.VALID_FLG = 1
)
SELECT * FROM TMP
ORDER BY EMP_CODE