== Relational Mapping - Relational Schema and DDL
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=== Notation
- Entities are denoted with capital letters and their attributes are defined (a1, a2, ..., an) where n is the number of attributes the entity has.
- Primary keys are denoted with underscore and boldness.
- Foreign keys are denoted with asterisk suffixing the attribute.
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=== Relations - Relational Schema
**USER**(**__user_id__**, first_name, last_name, email, password, phone)
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**RESTAURANT_OWNER**(**__user_id*__**(USER))
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**DELIVERY_MAN**(**__user_id*__**(USER))
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**CUSTOMER**(**__user_id*__**(USER))
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**ORDER**(**__order_id__**, **user_id***(USER), order_date, comment, status)
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**ITEM**(**__item_id__**, image_url, name, price, description)
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**ORDER_ITEMS**(**__order_id*__**(ORDER), **__item_id__**(ITEM), quantity, total_price)
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**INGREDIENT**(**__ingredient_id__**, name)
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**ITEM_INGREDIENT**(**__item_id*__**(ITEM), **__ingredient_id*__**(INGREDIENT), quantity)
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**DELIVERY_FIRM**(**__deliveryfirm_id__**, name)
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**DELIVERY_ASSIGNMENT**(**__deliveryfirm_id*__**(DELIVERY_FIRM), **__user_id*__**(DELIVERY_MAN))
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**RESTAURANT**(**__restaurant__id**, name, website_url, opening_time, closing_time, email, phone_number)
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**RESTAURANT_OWNERS**(**__user_id*__**(RESTAURANT_OWNER), **__restaurant_id*__**(RESTAURANT))
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**COSTS**(**__cost_id__**, **__restaurant_id*__**(RESTAURANT), date, amount, type)
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**EARNINGS**(**__earning_id__**, **__restaurant_id*__**(RESTAURANT), date, amount, source)
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**MENU**(**__menu_id__**, **__restaurant_id*__**(RESTAURANT), created_at, updated_at, name)
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**CATEGORY**(**__category_id__**, name, description)
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**RESTAURANT_CATEGORY**(**__category_id*__**(CATEGORY), **__restaurant_id*__**(RESTAURANT))
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**ITEM_CATEGORY**(**__category_id*__**(CATEGORY), **__item_id*__**(ITEM))
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**ADDRESS**(**__address_id__**, city, street, postal_code)
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**USER_ADDRESSES**(**__address_id*__**(ADDRESS), **__user_id*__**(USER))