title: Copy rows from one table to another, ignoring duplicates
body: <p>I have 2 tables (srcTable1 &amp; destTable) that have identical schemas. I am trying to copy all rows from srcTable to destTable and ignore the duplicates. I thought I could just add a WHERE clause with a subquery that would give me only the rows that aren't duplicates. However, it doesn't seem to work. I don't get any rows inserted or selected.</p>
  
  <pre><code>INSERT INTO destTable
  SELECT * FROM srcTable
  WHERE NOT EXISTS(SELECT * FROM destTable)
  </code></pre>
  
  <p>I realize I could do something like this:</p>
  
  <pre><code>INSERT INTO destTable
  SELECT * FROM srcTable
  WHERE MyKey IN (SELECT MyKey FROM destTable)
  </code></pre>
  
  <p>However, my tables have multiple keys and I can't think of how you could do this with multiple keys.</p>
  
  <p>Any idea what I'm doing wrong or do you have any better ideas?</p>