题解 | 更新员工信息表

select EMPLOYEE_ID,POSITION,LAST_UPDATE_DT
from 
(select EMPLOYEE_ID,POSITION,LAST_UPDATE_DT ,row_number() over (partition by  EMPLOYEE_ID order by LAST_UPDATE_DT desc) as rk 
from 

(select EMPLOYEE_ID,POSITION,LAST_UPDATE_DT 
from EMPLOYEE_INFO
union all 
select EMPLOYEE_ID,NEW_POSITION as POSITION,UPDATE_DT as LAST_UPDATE_DT
from EMPLOYEE_UPDATE) a 
) b
where rk=1