title: Can or Should an ERD Action involve more than 2 Entities?
body: <p>This is an problem about drawing ERD in one of my course:</p>
  
  <blockquote>
    <p>A local startup is contemplating launching Jungle, a new one stop
    online eCommerce site.</p>
    
    <p>As they have very little experience designing and implementing
    databases, they have asked you to help them design a database for
    tracking their operations.</p>
    
    <p>Jungle will sell a range of products, and they will need to track
    information such as the name and price for each. In order to sell as
    many products as possible, Jungle would like to display short reviews
    alongside item listings. To conserve space, Jungle will only keep
    track of the three most recent reviews for each product. Of course, if
    an item is new (or just unpopular), it may have less than three
    reviews stored.</p>
    
    <p>Each time a customer buys something on Jungle, their details will be
    stored for future access. Details collected by Jungle include
    customer’s names, addresses, and phone numbers. Should a customer buy
    multiple items on Jungle, their details can then be reused in future
    transactions.</p>
    
    <p>For maximum convenience, Jungle would also like to record credit card
    information for its users. Details stored include the account and BSB
    numbers. When a customer buys something on Jungle, the credit card
    used is then linked to the transaction. Each customer may be linked to
    one or more credit cards. However, as some users do not wish to have
    their credit card details recorded, a customer may also be linked to
    no credit cards. For such transactions, only the customer and product
    will be recorded.</p>
  </blockquote>
  
  <p>And this is the solution:
  <a href="https://i.stack.imgur.com/dU79w.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dU79w.png" alt="ERD Solutoin"></a></p>
  
  <p>The problem is the Buys action connect with 3 others entities: Product, Customer, and Card. I find this very hard to read and understand.</p>
  
  <p>Is an action involving more than 2 entities common in production? If it is, how should I understand and use it? Or if it's not, what is the better way of design for this problem?</p>