CF7 – existing mysql database

CFDB writes everything to its own table. It does not write to tables that you select. The table that it writes to does not have the structure you probably expect. http://cfdbplugin.com/?page_id=71

You can write your own PHP code and connect it to a hook in CFDB or one directly in CF7 (so you don’t need CFDB). Your code can receive form submissions. You can put in code to write that data it to your own table. The hook for CFDB is described: http://cfdbplugin.com/?page_id=747