How to sum values that appear on the same day?

I want to sum some values if they appear on the same day.

My very large spreadsheet has a date column and a widgets column:

Date        Widget
2010-10-28      15
2010-10-28      10
2010-10-28       9
2010-10-29      11
2010-10-29      14
2010-10-30      12
2010-11-01      19
2010-11-01      31
2010-11-01      20
2010-11-01      11
2010-11-01      42

I want to know the total number of widgets for each day. Since there are thousands of days on my spreadsheet, I can’t input each date manually, and there are not always the same number of entries for each day.

So how can I create a formula to do this? SUMIF seems to be the obvious choice but I can’t figure out a way of creating a conditional range.

Hi

You can use DataPivot TableRow Fields: drag Date from Available FieldsData Fields: drag Widget (display Sum- Widget).

See Widgets.ods: right click somewhere in A17:B22Edit Layout

You can even make groups: click somewhere in A18:A21 in then press F12 (or DataGroup and OutlineGroup)

Regards