title: When using multiple WHEN MATCHED statements, do they all execute, or does only one get executed?
body: <p>If I have multiple WHEN MATCHED statements in a MERGE statement, do they all execute if they're true?</p>
  
  <p>My example:</p>
  
  <pre><code>DECLARE @X bit = NULL;
  
  --skipping the MERGE statement, straight to WHEN MATCHED
  
  WHEN MATCHED AND A = 1
      @X = 0;
  WHEN MATCHED AND B = 1
      @X = 1;
  </code></pre>
  
  <p>What is the state of X in each of the 4 possibilities?</p>
  
  <pre><code>A|B|X
  0|0|?
  0|1|?
  1|0|?
  1|1|?
  </code></pre>
  
  <p>Basically, I'm curious if there's an implicit BREAK after each WHEN MATCHED clause.</p>