IBM and the Holocaust (2001) by Edwin Black is meticulously researched and highly informative.
It explains in detail how the Nazis used existing census information and instruments (Hollerith/IBM punched card machines) to identify Jewish people in the different occupied countries.
And how they they continued to use Hollerith/IBM machines to manage the sheer logistics of mass transportation to labour and extermination camps (of Jewish people, POWs, "subversives", etc)
And once in the camps... The infamous tattooed numbers on prisoners' wrists are actually their "Hollerith number", to match their punched card. To work them to death more effectively, you see, according to where each person's specific skills were most use.
Black holds IBM culpable for the assistance they rendered the Third Reich. I broadly agree with this view, but even if one doesn't, the book is still well worth reading as a very well-referenced factual account of how punched-card databases were used in the Holocaust.
Eg, the actions of René Carmille of the French statistics office and demographic service, who stymied various attempts at mass deportation from France by the simple measure of not having punched the column for "Jewish" on population registration cards.