title: Price History for each item in database
body: <p>I have this table</p>
  
  <pre><code>Transactions
  - id
  - user_id // this will point to which user did this transaction
  - item_id // this will point to which item in this transaction
  - date
  </code></pre>
  
  <p><br></p>
  
  <pre><code>Products
  - id
  - name
  </code></pre>
  
  <p><br></p>
  
  <pre><code>Items
  - id
  - product_id // this will point to which product this item is
  - name
  - price
  </code></pre>
  
  <p>The problem is, overtime, the item's price will change. <br>
  To prevent changes in the old transaction history's price <br>
  I need a way to keep old item's price.</p>
  
  <p>How can I make the right database design to solve this?</p>