The cleanest way is to use the --without-demo flag when initializing the database via Odoo's own CLI instead of relying on createdb alone:

odoo-bin -d your_database --without-demo=all -i base --stop-after-init

This tells Odoo not to load any demo data during the initial module installation.

If you must use createdb first and then initialize, your SQL workaround works but needs to run before any module is installed. A cleaner version that covers all modules:

UPDATE ir_module_module SET demo = False;

The proper long-term solution is to set it in your odoo.conf:

without_demo = all

This ensures no database created through that Odoo instance will ever load demo data, regardless of how it's initialized; no manual SQL needed each time.