title: sql update multiple rows, with condition in each row
body: <p>I have a table with columns A,B,C.</p>
  
  <p>I want to update column C if A and B (A, B together are unique) so the pseudo code looks like this:</p>
  
  <pre><code>update table 
  set (a = 1, b = 1, c = 1000)
      (a = 2, b = 2, c = 2000)
      (a = 3, b = 3, c = 3000)
  where a and b matches columns
  </code></pre>
  
  <p>How can I write this in SQL ?</p>