title: How should I structure bank cards entities into my database?
body: <p>Good afternoon.</p>
  <p>I'm working into a new module about personal finances in an application and in this case, I need to implement a new system to register bank cards that will be used to manage the current user transactions.</p>
  <p>The requirement differentiates between <strong>credit</strong> and <strong>debit</strong> cards; where some base fields are repeated and other are different.</p>
  <p>Here is the fields for every card type:</p>
  <ul>
  <li>Debit card:
  Code, ownerName, provider, model, initialAmount</li>
  <li>Credit card: Code, ownerName, provider, model, creditLimit, courtDate, PaymentDate</li>
  </ul>
  <p>As we see; both shares 4 fields.
  My answer is the following:</p>
  <p>Should I make two different tables? (one per card type). Or its correct to handle all fields into a unique abstract table called <strong>Card</strong> and provide a new field like <em>cardType</em>, which will differentiate the card type and handle the uncommon fields as nullables?</p>