Need help to create product variation database for pos system?

I want to create point of sale system for super shop which has multiple outlet in different location. i need to product variation for this system can you please help me out how can i develop best database structure for product variation. i'm implement something like this

Table:
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1. variations 
id, name
2.variation_values
id, variation_id, value
3. products
id, sku, name, category, brand [...other fields]
4. production_locations
product_id, location_id
5. product_variations
id, variation_id,  product_id, 
6. product_variation_values
id, product_id, product_variation_id, variation_value_id, sku [...other fields]
7. product_variation_location
id, product_id, production_variation_id, product_variation_value_id, location_id, available_stock

can you please explain it's look ok or need improvement?