se você estiver usando o SQL Server,
dateadd(DAY,0, datediff(day,0, created)) retornará o dia criado por exemplo, se a venda foi criada em '2009-11-02 06:12:55.000',
dateadd(DAY,0, datediff(day,0, created)) retornar '2009-11-02 00:00:00.000' select sum(amount) as total, dateadd(DAY,0, datediff(day,0, created)) as created
from sales
group by dateadd(DAY,0, datediff(day,0, created))
