SQL join

Hello,

First of all thank you for your great effort in building this plugin.

I am beginner programmer and faced the problem with joining two tables. I want to show the link to the PDF of what was generated by the form to user(s) on front end. To do that I guess I need SQL join, but it is very difficult for me to extract data to columns from “wpcf7pdf_data”. Could you share SQL of parsing wpcf7pdf_data into columns? Thank you so much in advance!