In this project, you will work with an e-commerce database. The database has products that consumers can buy from different suppliers. Customers can create an order and add several products in one order.

• Use SQL queries to retrieve specific data from a database
• Draw a database schema to visualize relationships between tables
• Label database relationships defined by the REFERENCES keyword in CREATE TABLE commands

To prepare your environment, open a terminal and create a new database called cyf_ecommerce:

createdb cyf_ecommerce

Import the file cyf_ecommerce.sql in your newly created database:

psql -d cyf_ecommerce -f cyf_ecommerce.sql

Open the file cyf_ecommerce.sql in VSCode and examine the SQL code. Take a piece of paper and draw the database with the different relationships between tables (as defined by the REFERENCES keyword in the CREATE TABLE commands). Identify the foreign keys and make sure you understand the full database schema.

Don't skip this step. You may one day be asked at interview to draw a database schema. Sketching systems is a valuable skill for back end developers and worth practising. If you're interested in systems design, you may also want to take a course on Udemy.

You can even draw relationship diagrams on GitHub:

erDiagram
    customers {
        id INT PK
        name VARCHAR(50) NOT NULL
    }
    customers ||--o{ orders : places

Write SQL queries to complete the following tasks:

• List all the products whose name contains the word "socks" cyf_ecommerce=# SELECT* FROM products WHERE product_name LIKE '%socks%';SELECT prod

• List all the products which cost more than 100 showing product id, name, unit price, and supplier id cyf_ecommerce=# SELECT prod_id,product_name, unit_price, supp_id cyf_ecommerce-# FROM product_availability pa INNER JOIN products p on (pa.prod_id=p.id) cyf_ecommerce-# WHERE unit_price>100;

• List the 5 most expensive products SELECT product_name , unit_price FROM product_availability pa INNER JOIN products p on (pa.prod_id=p.id) order by unit_pr desc Limit 5;

• List all the products sold by suppliers based in the United Kingdom. The result should only contain the columns product_name and supplier_name cyf_ecommerce=# select p.product_name,s.supplier_name cyf_ecommerce-# from suppliers s left join cyf_ecommerce-# product_availability pa on (s.id = pa.supp_id) cyf_ecommerce-# left join products p on (p.id =pa.prod_id) cyf_ecommerce-# where s.country ='United Kingdom' cyf_ecommerce-# order by pa.unit_price desc;

• List all orders, including order items, from customer named Hope Crosby cyf_ecommerce=# select * from orders o inner join cyf_ecommerce-# order_items oi on (o.id = oi.order_id) cyf_ecommerce-# inner join customers c on (o.customer_id =c.id) cyf_ecommerce-# where c.name = 'Hope Crosby';

• List all the products in the order ORD006. The result should only contain the columns product_name, unit_price, and quantity cyf_ecommerce=# select p.product_name, pa.unit_price, oi.quantity from products p inner join product_availability pa on (p.id=pa.prod_id) inner join order_items oi on (oi.product_id=p.id and oi.supplier_id=pa.supp_id) inner join orders o on (o.id = oi.order_id) where o.order_reference ='ORD006';

• List all the products with their supplier for all orders of all customers. The result should only contain the columns name (from customer), order_reference, order_date, product_name, supplier_name, and quantity

cyf_ecommerce=# select c.name,o.order_reference, o.order_date, p.product_name, s.supplier_name, oi.quantity cyf_ecommerce-# from products p cyf_ecommerce-# left join order_items oi on (oi.product_id=p.id) cyf_ecommerce-# inner join suppliers s on (s.id=oi.supplier_id) cyf_ecommerce-# inner join orders o on (oi.order_id=o.id) cyf_ecommerce-# inner join customers c on (c.id=o.customer_id);

• The cyf_ecommerce database is imported and set up correctly
• The database schema is drawn correctly to visualize relationships between tables
• The SQL queries retrieve the correct data according to the tasks listed above
• The pull request with the answers to the tasks is opened on the main branch of the E-Commerce repository