title: Is there any way to get owner ids who have more than 2 books using PostgreSQL query?
body: <p>In <code>libraries</code> table, there are <code>owner_id</code> and <code>book_id</code>.</p>
  
  <p>Each <code>owner</code> can have only one <code>book</code>.
  For example,</p>
  
  <pre><code>  id|owner_id|book_id
    3 |  2     | 1
    5 |  2     | 1
  </code></pre>
  
  <p>But now some owners have more than 2 books.</p>
  
  <pre><code>  id|owner_id|book_id
    9 |  5     | 1
    11|  5     | 2
  </code></pre>
  
  <p>Is there any way to get <strong>owner ids</strong> who have more than <strong>2 books</strong> using <strong>PostgreSQL query</strong>?</p>