I am unable to run “drush site-install” without getting errors

When I open Terminal on the david/Sites/animals directory, and I run drush site-install --db-url=mysql://david:root@localhost:3306/animals, the get the following error.

In SiteInstallCommands.php line 152: Drush was unable to drop all tables because mysql was not found, and therefore Drupal threw an AlreadyInstalledException. Ensure mysql is available in your PATH.

Did I write the correct command?