Find closest time match with multi criteria, return another value

Hello! Im hopeful I could borrow your time and knowledge to solve a problem I have. The excel file I am working with is actually 5 different spreadsheets, each with over a half million lines of data. Here is my dilemma:

Zone is sometimes UNK(“Unknown”) in specific columns but is known in others. This is my problem.

What I need is a formula that looks at the user id, date and closest time match to answer for the “unknown” zone.

See attachment for example. I really appreciate any help you can provide.

Regards,
Daniel

Please try at E2 and drag down

=IF(B2="unk",INDEX($B$2:$B$5,MATCH(AGGREGATE(15,6,ABS(D2-$D$2:$D$5),2),INDEX(ABS(D2-$D$2:$D$5),),)),"")

Hi
Try this in E2:

Formula:

Please Login or Register  to view this content.