SQL query to group by day

Question

I want to list all sales, and group the sum by day.

Sales (saleID INT, amount INT, created DATETIME)

NOTE: I am using SQL Server 2005.

Answer 1

For SQL Server:

GROUP BY datepart(year,datefield), 
    datepart(month,datefield), 
    datepart(day,datefield)

or faster (from Q8-Coder):

GROUP BY dateadd(DAY,0, datediff(day,0, created))

For MySQL:

GROUP BY year(datefield), month(datefield), day(datefield)

or better (from Jon Bright):

GROUP BY date(datefield)

For Oracle:

GROUP BY to_char(datefield, 'yyyy-mm-dd')

or faster (from IronGoofy):

GROUP BY trunc(created);

For Informix (by Jonathan Leffler):

GROUP BY date_column
GROUP BY EXTEND(datetime_column, YEAR TO DAY)