Online shopping (3 out of 5)

Since this question lacks specific context, we can infer that "E-commerce (3 of 5)" refers to a prompt for discussing SQL issues related to E-commerce. You are likely being asked to address problems or implement solutions concerning an E-commerce data structure using SQL. This might involve tasks such as managing data transactions, querying user information, tracking order histories, and more. Topics could range from normalization to data analysis aimed at improving business processes, among other areas. To effectively respond to such inquiries, it is essential to grasp how E-commerce systems function, including the types of data they encompass and the methods for accessing that data through SQL commands. Important points to keep in mind: E-commerce systems generally consist of users, products, transactions, and occasionally, product categories. The structure of an E-commerce database can be intricate and may involve different relationships, such as Many-to-One and One-to-Many. A solid understanding of SQL syntax is crucial for providing effective answers.

Let’s take a look at the SQL query designed to fetch all the products purchased by a specific user. We have three tables: 'users', 'products', and 'orders', where the 'orders' table includes foreign keys that link to both the 'users' and 'products' tables: SELECT products . * FROM products JOIN orders ON products . product_id = orders . product_id JOIN users ON orders . user_id = users . user_id WHERE users . user_id = < specified_user_id > ; This SQL query retrieves all products that the specified user has purchased.

Let's examine an SQL query that retrieves the average order value for a given product. We assume the presence of 'products', 'orders', and 'order_items' tables, with 'order_items' containing foreign keys that link to both the 'orders' and 'products' tables: SELECT AVG ( order_items . price ) as 'Average Order Value' FROM order_items JOIN orders ON order_items . order_id = orders . order_id JOIN products ON order_items . product_id = products . product_id WHERE products . product_id = < specified_product_id > ; This SQL query determines the average order value for the designated product.