Merely populating your DB was infringement of their copyright. So is "just you organizing data on your own machine". Making copies, and making derivative works

Merely populating your DB was infringement of their copyright. So is "just you organizing data on your own machine". Making copies, and making derivative works (transforming the work in some way), are both exclusive rights held by the author of a work. Distribution is another of those rights, and infringing any of the rights is illegal. You do not need to distribute anything, or induce distribution, to be infringing someone's copyright. The Copyright Act isn't terribly long or complex, and there are many good summaries of it online if anything's confusing. You might want to read it. Ignorance of the law is not a defense should you be sued.