title: Where should I put the following method?
body: <p>I have 2 tables with the relationship:</p>
  
  <pre><code>Purchase 1:m Payment
  </code></pre>
  
  <ul>
  <li>Each purchase has a primary key "purchaseId".</li>
  <li>Each payment has a primary key "transactionId" and a foreign key "purchaseId";</li>
  </ul>
  
  <p>I have a DAO class for each table. Now I want to implement a function </p>
  
  <pre><code>List&lt;Payment&gt; findPaymentsByPurchaseId(int purchaseId)
  </code></pre>
  
  <p>To make the API feels more intuitive, should I put this function in</p>
  
  <ol>
  <li>PurchaseDAO to indicate "if I want to find anything based on Purchase information, I just call a function in PurchaseDAO"</li>
  <li>PaymentDAO to indicate "if I want to find Payment information, I just call a function in PaymentDAO"</li>
  </ol>
  
  <p>Which one do you feel more intuitive?</p>