update EMP set VALID_FLG='0' where EMP_CODE = (
select EMP.EMP_CODE from EMP
inner join EMP_INVALID on EMP.EMP_CODE=EMP_INVALID.EMP_CODE
where EMP.USER_UPDATE_DATETIME > EMP_INVALID.USER_UPDATE_DATETIME and EMP.VALID_FLG<>'1'
)