In Excel 2007 I have a sheet "sheet1" which has a part number in a
cell. (A5)
I want cell (D5) to have a data validation drop down menu which is
populated from "sheet2".

Sheet2 data looks something like this:

Column A Column B
partnumber1 tradename1
partnumber1 tradename2
partnumber2 tradename3
partnumber3 tradename4

The drop down in (D5) sheet1 should only contain tradenames which have
partnumber matching (A5) sheet1.


Ideas?
Can I use SQL syntax in the data validation lookup?