从sql表计算每日平均销售额

Question

我想从我的sql表中计算每日平均销售额.我尝试使用以下查询,但它提供错误说"关键字选择附近的语法不正确"

select avg(select sum(total) from canteen group by date) as average from canteen

Answer 1

不嵌套聚合函数.这是您想要获得每个日期的总和:

select day, sum(total)
from canteen
group by day;

您可以使用子查询获得平均值:

select avg(total)
from (select day, sum(total) as total
      from canteen
      group by day
     ) c;

或者,更简单的替代方案:

select sum(total) / count(distinct day)
from canteen;