I'm stumped on a particular problem with some data that's imported to me. I have zero control over how the data is coming in. (Just to clarify that point).
I have two columns and 107,000 rows.
Column A has an ID#, Column B has the corresponding Date.
The issue I have is that Column A can have multiple identical values, and the corresponding date value in Column B has different or same dates.
I'm looking to add column C with a way to look up the cell in Column A, check it against the rest of column A, find any matches, and then return the Max/most recent date from column B for that ID#.
Please try:
=MAX(IF(A:A=A1,B:B))
entered with Ctrl+Shift+Enter and copied down to suit.
I'm afraid this could be quite slow.
I did not limit the range because I assumed 107,000 rows was an approximation. However this is slow even for 1,000 rows, so for emphasis I repeat part of @XOR LX's comment:
Even reducing the number of rows being referenced by a factor of 10 will have a significant improvement on calculation speed.