您可以尝试以下查询：

SELECT
    Date,
    100.0 * COUNT(attendance) / COUNT(*) AS perc_attendance
FROM yourTable
WHERE Date BETWEEN '2018-01-01' AND '2018-01-02'
GROUP BY
    Date;

这假设给定的用户在给定的日期最多只出现一次。它还假设 Date 列是实际的日期列，而不仅仅是文本。

演示

如果尝试显示为新表，则可以使用此查询，但必须创建一个：

SELECT Date,100.0 * COUNT(attendance) / COUNT(*) AS attendancepercent
FROM Table WHERE Date BETWEEN '2018-01-01' AND '2018-01-02'
GROUP BY Date;

select v.date1 , case when s.no_people is null and v.showup_people then 100
when v.showup_people is null and s.no_people is not null then 0
else (v.showup_people / (v.showup_people + s.no_people))*100  end outcome 

from
(select count(*) as no_people , date as date1
   from yourTable
   where attendance is null
   group by date) s
   right outer join
   (select count(*) as showup_people , date as date1
   from yourTable
   where attendance is not null
   group by date) v
on(v.date1 = s.date1)

将表名中的from表替换为。。
不管你有多少次约会，这都是有效的。这种情况是因为null+mysql中的一个数字表示null。在oraclesql中，您可以只使用最后一个else语句。
这是一个演示