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The key question is whether it is a spinning HDD or SSD.
Single overwrite with any data is fine for HDD. Unless the CIA are likely to be looking at it.
SSD needs the manufacturer's wipe utility as there is no other way of accessing the individual blocks.
If in any doubt, physical destruction works for either.
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I thought you were talking about just public (all can read) + private (some users can read) data, but it sounds like you want to control read permissions to individual rows based on user.
I don't think this is a job for Excel really.
At least not if you want to do it in real-time, rather than e.g. compile data per user once a day.
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https://en.wikipedia.org/wiki/The_Hero_with_a_Thousand_Faces