Saved from a previous post:

If you want exact matches for just two columns (and return a value from a

third), you could use:

=index(othersheet!$c$1:$c$100,

match(1,(a2=othersheet!$a$1:$a$100)

*(b2=othersheet!$b$1:$b$100),0))

(all in one cell)

This is an array formula. Hit ctrl-shift-enter instead of enter. If you do it

correctly, excel will wrap curly brackets {} around your formula. (don't type

them yourself.)

Adjust the range to match--but you can only use the whole column in xl2007.

This returns the value in othersheet column C when column A and B (of

othersheet) match A2 and B2 of the sheet with the formula.

And you can add more conditions by just adding more stuff to that product

portion of the formula:

=index(othersheet!$d$1:$d$100,

match(1,(a2=othersheet!$a$1:$a$100)

*(b2=othersheet!$b$1:$b$100)

*(c2=othersheet!$c$1:$c$100),0))

============

If there is only one match and you're bringing back a number (or 0 if there is

no match for all the criteria), you can use:

=sumproduct(--(othersheet!a1:a10=a1),

--(othersheet!b1:b10=b1),

(othersheet!c1:c10))

Adjust the ranges to match--but you can't use whole columns (except in xl2007).

=sumproduct() likes to work with numbers. The -- stuff changes trues and falses

to 1's and 0's.

Bob Phillips explains =sumproduct() in much more detail here:

http://www.xldynamic.com/source/xld.SUMPRODUCT.html
And J.E. McGimpsey has some notes at:

http://mcgimpsey.com/excel/formulae/doubleneg.html