Autommatically random price and image for variants

Hi,

By default, when a variant is generated by HikaShop, no price is assigned to the variant.
And when no price is set for a variant, it will automatically use the price of the main product when using it on the frontend. But on the backend, you'll see it as no price set.
If you see a price set automatically in the variant in the backend after the variant is generated, then it means that you probably have a mass action setting that price. So I would recommend checking your mass actions in the menu System>Mass actions.
If it's not a mass action, then it could be a custom plugin, or some other code customization at play here.

Hi,

Then, it just means that you deleted entries of the table hikashop_product without deleting the corresponding entries in the tables hikashop_price and hikashop_file.
So when a variant is created, if there are already entries in hikashop_price / hikashop_file you see them.
The best is to clean your tables with a MySQL query.
For example:

DELETE a FROM #__hikashop_price as a LEFT JOIN #__hikashop_product AS b ON a.price_product_id = b.product_id WHERE b.product_id IS NULL;

Yes, exactly.
You can also do it on hikashop_product_category for the link between products and categories, and on hikashop_product_related for related products, options and bundled products.