title: Biq-query: add new key:val in json
body: <p>How can I add a new key/val pair in an already existing JSON col in bigqyery using SQL (big query flavor).</p>
  <p><a href="https://i.stack.imgur.com/OffV3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OffV3.png" alt="enter image description here" /></a></p>
  <p>To something like
  <a href="https://i.stack.imgur.com/MK03C.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MK03C.png" alt="enter image description here" /></a></p>