One verified attempt to assassinate President Trump: https://en.m.wikipedia.org/wiki/Attempted_assassination_of_Donald_Trump Several others rumored. Of course our fake news media did not cover any of them. They in fact probably cheered the attempt - or were upset the attempts failed.
Donald Trump was not President, or even President-elect at that time.
There was an attempted assassination of President-elect Roosevelt in 1933. The assassin missed the President-elect but killed Anton Cermak, the mayor of Chicago.