title: Sql Query for finding a certain frequency distribution
body: <p>This table is updated whenever a customer buys anything:</p>
  <h3>table 1</h3>
  <ul>
  <li>customerid</li>
  <li>item</li>
  </ul>
  <p>I want to find out a query to know the frequency distribution of number of customers and number of items bought. For example the number of customers who have bought 1 item, 2 items and so on.</p>