To add ACF fields to the WordPress database (e.g. when using a seeder), you need to add each ACF field as a row into the wp_posts table using the post_type value of acf-field.
This guide assumes that you have defined the fields with PHP and are seeding posts directly into the WordPress database.
Note: You can also create ACF Groups in a similar way using acf-field-group post_type. I will cover this in a separate gist.
Note: The only practical use case for this is a database seeder (e.g. for demo data) - any other interaction with ACF and the WordPress database should really be done via the plugin itself.