xo/usql ? reverse-engineered prompt

Build me a universal command line SQL client that feels like psql, but works across a bunch of databases like Postgres, MySQL, SQLite, SQL Server, and Oracle.

I want to connect with a database URL, open an interactive shell, and run SQL plus the usual slash style helper commands. It should show a friendly prompt, support variables, backtick style shortcuts, autocomplete based on the current database, syntax highlighting, and basic terminal visuals when possible. It should also make it easy to inspect what drivers are available, and switch between different databases in a natural way. If it helps, look up current docs online for any tricky database connection details.

Make it polished enough that I can use it like a real everyday tool from the terminal, with good help text, clear errors, and support for both running one off commands and staying in an interactive session.