title: Updating and join on multiple rows, which row's value is used?
body: <p>Let's say I have the following statement and the inner join results in 3 rows where a.Id = b.Id, but each of the 3 rows have different b.Value's.  Since only one row from tableA is being updated, which of the 3 values is used in the update?</p>
  
  <pre><code>UPDATE a
  SET a.Value = b.Value
  FROM tableA AS a
  INNER JOIN tableB as b 
  ON a.Id = b.Id
  </code></pre>