[GNC] Help with SQL commands

[Fred Tydeman]

I had GnuCash create a SQL database (sqlite3).

I have three different SQL GUI programs:
  dbeaver-ce, SQLiteStudio, DB_Browser

I have found three online pages about SQL and GnuCash:
  https://wiki.gnucash.org/wiki/SQL
  https://wiki.gnucash.org/wiki/GnuCash_SQL_Examples
  https://wiki.gnucash.org/wiki/images/8/86/Gnucash_erd.png

I am trying to create SQL queries to find errors in my GnuCash setup:
  List of "stocks" no longer owned, but still getting Online Quotes:
  List of "stocks" still owned, but not getting Online Quotes:
  List of "stocks" in more than one Namespace:
  List of "stocks" in more than one Trading account:

I can figure out some of the table columns that I need,
but need help creating the full queries.

I am running on Fedora Linux (35 thru 43) on Intel x86_64 with GnuCash 5.12
and 5.13