Excel formula to extract a specific record

Question

I have an excel spreadsheet with 250 accounts, each with a bunch of transaction records. I need to extract a date where an interest rate has changed. There are 250000+ records.

It looks like this:

ACCT                    CEL-INT-RATE    LTD-INT-BILL    FileDate
0006365290140074793     84.00           1479.43         20131007
0006365290140074793     84.00           1479.43         20131012
0006365290140074793     84.00           1479.43         20131014
0006365290140074793     84.00           2598.55         20131107 <---
0006365290140074793     21.00           2598.55         20131111
0006365290140074793     21.00           2598.55         20131129
0006365290140074793     21.00           2598.55         20131204

I need the date '20131107', which I marked with <---, where the interest rate was last at 84.00, before changing to 21.00, for the account 0006365290140074793

Can anyone help with this formula.

Thanks in advance

Answer 1

This is more of a power user function than a coding one but... '=IF(A2=A3,IF(B3<B2,"<---",""),"")

Used this fill down for a column and the <--- will identify when rate goes from 84 to 21 as indicated in sample data.

However I'm not sure what you mean by extract... is this a one time thing or something that needs to be automated? or just quickly identified? too many unknowns to really look deep into this. What's the use case? How does this need to work and what are the expected results?

AMENDED:

A welcome comment pointed out that the filedate being returned was that of the lower int-rate when the upper date was requested. This can be achieved by altering the formula as indicated in '=IF(A2=A3,IF(B2>B3,"<---",""),"") or visually: