I use the following for something similar. It might be what you are looking
for: -

=IF(ISERROR(INDEX(B1:B12500,SMALL(IF(A1:A12500=D1, ROW(B1:B12500),""),ROW()))=FALSE),"",(INDEX(B1:B12 500,SMALL(IF(A1:A12500=D1,ROW(B1:B12500),""),ROW() ))))

Enter as Array Formula CTRL+SHIFT+ENTER

Copy this down as many rows as you think there are unique numbers (say 100
rows)

Column A would be your Invoice Numbers
Column B would be your Purchase order Numbers
D1 would be the Purchase order number you are searching for



"Abhijeet" wrote:

hi , i have data stored in excel as column a- Purchase order no column b-
Invoice no i want to query basis purchase order no & result should give
mutiple invoice no stored agst one purchase order no how do i do this using
lookup or something !