Find Duplicates, check value in another column for each duplicate

I am trying to write a fairly simple formula but I do not know how to complete it. I believe I need to use Index and Match but am stumped.

I have attached a sample sheet with the formula requirement written in plain English.

Essentially, it is checking that where a duplicate value exists in column B, check the values for both duplicates in column D and then return a result. However for usability I have set up the worksheet a bit differently with an additional column that identifies duplicates that preferably needs to be taken into account - as this is part of a larger file and process.

not sure if i understand your requests in the workbook, but see if this gives yoy what you want?

=IF(C5="Y",VLOOKUP(B5,B6:$B$22,1,FALSE),"N")

try this in row 2 (any column) and let me know if this is what you need for the 2nd part?

=IF(C1="Y",VLOOKUP(VLOOKUP(B1,B2:$B$22,1,FALSE),B2:$D$22,3,FALSE),"N")

see if this works - start in, say, H2 and drag-fill down:

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Originally Posted by FDibbins

try this in row 2 (any column) and let me know if this is what you need for the 2nd part?

=IF(C1="Y",VLOOKUP(VLOOKUP(B1,B2:$B$22,1,FALSE),B2:$D$22,3,FALSE),"N")

Thanks, this is getting close. What your formula is doing is finding any instances of the B.Value in the cells below it, and checking for the value in column D. The issue then becomes - what about when a duplicate value needs to check the cells above it? All duplicates need to be checked against each other.
For example, if I could write a formula like this, it might give me the value required in most instances - however it still leaves the problem of what if there is more than 1 duplicate - the vlookup will only check the first value it finds, not the next.
=IF(C5="Y",VLOOKUP(VLOOKUP(B5,B2:$B$4 & B6:$B$22,1,FALSE),B2:$B$4 & B6:$D$22,3,FALSE),"N")
=IF(C6="Y",VLOOKUP(VLOOKUP(B6,B2:$B$5 & B7:$B$22,1,FALSE),B2:$B$5 & B7:$D$22,3,FALSE),"N")

---------- Post added at 12:28 PM ---------- Previous post was at 12:25 PM ----------

Originally Posted by icestationzbra

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Yes this works. Added bonus - I actually understand what it is doing.

One further question, is there a way of limiting this calculation / formula to only the "used range" in the columns? I have 30 formula and 10,000 rows in the file I am working with and my macros are taking a long time to run so I am looking at optimising everything.

Edit: the "Used Range" changes daily.

i am on Excel 2007 and your profile says that you are on 2003 (although your sample workbook was XLSX). i do not know if this suggestion works in 2003 (in its entirety), so you may have to google it if it does not work exactly this way. if you want another approach, revert here and someone (or i, whoever gets to it first) will help.

the simplest way to accomplish this would be to use the TABLE feature in Excel - Excel Tables autoextend their ranges and autopopulate their formulae.

in the sample workbook that you attached in post #1, highlight cell A1 and then using the keyboard invoke the Table feature (CTRL + T or ALT > N > T).

once that feature is invoked, it will ask you to provide the range of your table. use A1:E22 as the range for your table, and DO NOT forget to check the box for "my table has headers".

once you accomplish this successfully, you will see that the colour of the table has change to the default theme offered by Excel. at this time, while your table range is highlighted, you may attempt to change the theme (or Table Style) by using the keyboard shortcut ALT > JT > S and looking through other options.

once your table is established, put the formula in cell E2 and drag-fill down to E22. after this, whenever you add a new "contiguous" row of record, the table will autoextend and auto-drag-fill any formula down to the latest row.

i have done this for you in the attached file.

if you want to use Dynamic Named Ranges, a formulaic way of autoextending ranges, you will be well served, too.

why are you using whole column ranges when you have only 11000 rows of data? Excel 2007 has a million rows in the entire column. fix that and try for performance.