title: postgresql: jsonb update multiple keys in one query
body: <p>I have the following postgresql rows as JSONB row:</p>
  
  <pre><code>{age:26}
  </code></pre>
  
  <p>And I would like to replace it so that that i looks like this:</p>
  
  <pre><code>{age: 30, city: "new york city"}
  </code></pre>
  
  <p>How can I do this in postgressql? Someone metioned using <code>jsonb_set()</code>, but I haven't seen any examples of updating multiple keys in one query.</p>