hsqldb计算每一天

Question

有桌子

id|date|somefield

我需要计算一年中每一天的参赛人数

select EXTRACT (DAY_OF_YEAR FROM date) as day, id from table

工作正常

但是当我尝试

时

select EXTRACT (DAY_OF_YEAR FROM date) as day, count(*) from table

失败

select count(*) from table group by EXTRACT (DAY_OF_YEAR FROM date)

也失败了

Answer 1

您需要添加group by表达式。这是一些伪代码，我马上就会编写一个SqlFiddle。

select EXTRACT (DAY_OF_YEAR FROM date) as day, 
count(*) 
from table
group by EXTRACT (DAY_OF_YEAR FROM date)

SQLFIDDLE（使用MYSQL） http://sqlfiddle.com/#!2/42c9e/10