> my genuine desire to take some sensible measures to reduce violent crime

How is a database a sensible measure? Even in your example (like on TV), the crime has already been committed.

We see this in the real world too. After the Pulse massacre, they looked up the gun. Sure enough, it belonged to the shooter, who passed background checks, took training courses, and went through psych evaluations. All of the above (frequently touted) measures were completely ineffective at preventing or even mitigating the disaster.

I too have a genuine desire to stop mass shootings, but the genuine-ness of my desires doesn't necessarily mean effective-ness.