I have no idea how well employers have access to that sort of stuff though, but I know if you are committed to a psychiatric hospital it's on your record.

making any sort of database is just an awful, awful idea. It would be a massive HIPAA violation, it would be a deterrent to seeking care, it would be unnecessary profiling.

What constitutes mental issues to the point of barring them from buying a gun or being hired somewhere?

Answer: Per federal law, being adjudicated as mentally incompetent by a court of law, or committed involuntarily to a psychiatric institution.

And how far in the past can the mental issues be for them to be removed from the database?

Generally that is defined in state laws. People have temporary psychotic breaks and may recover spontaneously, or respond well to therapy over a period of years. Here in California someone who has been involuntarily committed is barred from owning a firearm for five years.

A person who has been adjudicated as mentally incompetent can challenge the ruling at any time.

is not to have such a data base, but to simply make sure everybody is armed. Sure, millions will die, but they will be free of tyranny!

And for those young people who want to pursue a career in the military, i.e. Naval Academy, etc, having taken an anti-depressant at any point is a deal breaker.

The problem here is that when somebody may NEED medication, they don't take it, as they don't want to be stigmatized and denied career/educational opportunities.

As far as gun control is concerned, doesn't it only affect those who have been involuntarily hospitalized or identified by a psychiatrist as a threat?

All Seeing Eye?