SQL query to group by day - sql

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

if you're using SQL Server,
dateadd(DAY,0, datediff(day,0, created)) will return the day created
for example, if the sale created on '2009-11-02 06:12:55.000',
dateadd(DAY,0, datediff(day,0, created)) return '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))

Answer 2

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)

Answer 3

If you're using MySQL:
SELECT
DATE(created) AS saledate,
SUM(amount)
FROM
Sales
GROUP BY
saledate
If you're using MS SQL 2008:
SELECT
CAST(created AS date) AS saledate,
SUM(amount)
FROM
Sales
GROUP BY
CAST(created AS date)

Answer 4

For PostgreSQL:
GROUP BY to_char(timestampfield, 'yyyy-mm-dd')
or using cast:
GROUP BY timestampfield::date
if you want speed, use the second option and add an index:
CREATE INDEX tablename_timestampfield_date_idx ON tablename(date(timestampfield));

Answer 5

actually this depends on what DBMS you are using but in regular SQL convert(varchar,DateColumn,101) will change the DATETIME format to date (one day)
so:
SELECT
sum(amount)
FROM
sales
GROUP BY
convert(varchar,created,101)
the magix number 101 is what date format it is converted to

Answer 6

If you're using SQL Server, you could add three calculated fields to your table:
Sales (saleID INT, amount INT, created DATETIME)
ALTER TABLE dbo.Sales
ADD SaleYear AS YEAR(Created) PERSISTED
ALTER TABLE dbo.Sales
ADD SaleMonth AS MONTH(Created) PERSISTED
ALTER TABLE dbo.Sales
ADD SaleDay AS DAY(Created) PERSISTED
and now you could easily group by, order by etc. by day, month or year of the sale:
SELECT SaleDay, SUM(Amount)
FROM dbo.Sales
GROUP BY SaleDay
Those calculated fields will always be kept up to date (when your "Created" date changes), they're part of your table, they can be used just like regular fields, and can even be indexed (if they're "PERSISTED") - great feature that's totally underused, IMHO.
Marc

Answer 7

For oracle you can
group by trunc(created);
as this truncates the created datetime to the previous midnight.
Another option is to
group by to_char(created, 'DD.MM.YYYY');
which achieves the same result, but may be slower as it requires a type conversion.

Answer 8

The simplest and intuitive solution for MySQL is:
GROUP BY day(datefield)

Answer 9

use linq
from c in Customers
group c by DbFunctions.TruncateTime(c.CreateTime) into date
orderby date.Key descending
select new
{
Value = date.Count().ToString(),
Name = date.Key.ToString().Substring(0, 10)
}