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) rk
    from (
        select EMPLOYEE_ID, POSITION, LAST_UPDATE_DT
        from EMPLOYEE_INFO
        union all
        select EMPLOYEE_ID, NEW_POSITION, UPDATE_DT
        from EMPLOYEE_UPDATE
    ) t1    
) t2
where rk=1
order by EMPLOYEE_ID