title: Update rows using data within the same table SQL
body: <p>I have a table which looks like this</p>
  <p>messageId | conversationId | campusA | campusB</p>
  <pre><code>1              1        campusA
  2              1
  3              1
  4              1
  5              2
  6              2
  7              2                   campusB
  </code></pre>
  <p>As we can see multiple messages are linked to the same conversationId and we have campus information for some of the records. Using this information I want to update remaining empty rows that are linked to the same conversationId. For example, I can see campusA is linked to conversationId 1. Using this information, I want to update the remaining 3 rows that have the same conversationId as the first record.</p>
  <p>I was having trouble figuring this out and was wondering what would be the most efficient way to go around this? Thank you in advance!</p>