How do I sum #s in a column based on dates in another column

[Guest]

I have a spreadsheet that has MANY values. One column provies the size of a
file, and another corresponding column provides the date the file was created
(month, day, year -- and some have times). What kind of formula/macro can I
create that will sum the sizes of the files that correspond to certain dates?
For Example:
COLUMN A COLUMN B
34 Jul 20, 2004
2009 Jul 20, 2004
3 Aug 11, 2005
20006 Feb 3, 2006 11:15
23 Feb 3, 2006 11:15

 

[Guest]

If your add-ins are installed, use the conditional sum wizard via the
tools-->Wizards menu path.

Otherwise, use SUMIF as an array formula.

 

[Bernard Liengme]

Look in Help to learn about SUMIF
or try SUMPRODUCT, see
http://www.xldynamic.com/source/xld.SUMPRODUCT.html
http://mcgimpsey.com/excel/formulae/doubleneg.html

The come back if more help needed

 

[Guest]

Actually that doesn't help too much. You see, my data set is about 85000
values (yes i have info on multiple sheets, but that's a different problem)
So the date fields range from jan2004 to aug2006. I can use the sumif, if
there weren't too many date values to choose from--i guess i just hard code
them?--, but I have too many. Is there anything else that I can use? Or
is there a way to use sumproduct/sumif for values that are not static?

I tried to use sumproduct and do a monthly comparison but it didn't work.
So basically:

if(month/day/year <=date in COLUMNB <= month/day/year)
then sum COLUMNA