title: Update table based on column in another table
body: <pre><code>UPDATE bad_table,good_table
  SET bad_table.post_content = good_table.post_content    
  WHERE bad_table.post_type = 'post' AND 
  bad_table.post_date = good_table.post_date
  </code></pre>
  
  <p>This is my code for getting one whole column from one table to another, based on a date value, which I found is unique for this case. However, I get nothing.</p>
  
  <p>If I select this, like so:</p>
  
  <pre><code>SELECT * FROM bad_table,good_table
  WHERE bad_table.post_type = 'post' AND 
  bad_table.post_date = good_table.post_date
  </code></pre>
  
  <p>...I get all the rows I would expect. What am I doing wrong?</p>