这是你想要的吗？

select max(athr_name), max(post_date), page_nm, 
       visit_date, sum(visit), sum(visitors)
from t
group by page_nm, visit_date;

首先，需要用最后一个值填充nulls值。您的查询可能如下所示：

SELECT athr_name, 
       post_date, 
       page_nm, visit_date, 
       sum(visit), 
       sum(visitors)
from (
    select nvl(athr_name, LAST_VALUE(athr_name, TRUE)
                                              OVER (ORDER BY page_nm, athr_name NULLS LAST ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)) as athr_name,
           nvl(post_date, LAST_VALUE(post_date, TRUE)
                                              OVER (ORDER BY page_nm, post_date NULLS LAST ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)) as post_date,
           page_nm,
           visit_date,
           visit,
           visitors
    from your_table) as tmp_view
GROUP BY athr_name, post_date, page_nm, visit_date;

更新：
如果您可能没有相应的用户名或某个页面的发布日期，最好使用此查询来保留此信息：

SELECT athr_name, post_date, page_nm, visit_date, sum(visit), sum(visitors)
from (
         select name_view.athr_name as athr_name,
                date_view.post_date as post_date,
                main.page_nm,
                main.visit_date,
                main.visit,
                main.visitors
         from your_table main
                  LEFT JOIN (select athr_name, page_nm, row_number() over (PARTITION BY page_nm) as rn
                             from your_table
                             where athr_name is not null) name_view
                            ON main.page_nm = name_view.page_nm AND name_view.rn = 1
                  LEFT JOIN (select post_date, page_nm, row_number() over (PARTITION BY page_nm) as rn
                             from your_table
                             where post_date is not null) date_view
                            ON main.page_nm = date_view.page_nm AND date_view.rn = 1) as tmp_view
GROUP BY athr_name, post_date, page_nm, visit_date;