title: Left join or select from multiple table using comma (,)
body: <p>I'm curious as to why we need to use <code>LEFT JOIN</code> since we can use commas to select multiple tables.</p>
  
  <p>What are the differences between <code>LEFT JOIN</code> and using commas to select multiple tables.</p>
  
  <p>Which one is faster?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>   SELECT mw.*, 
            nvs.* 
       FROM mst_words mw 
  LEFT JOIN (SELECT no as nonvs, 
                    owner, 
                    owner_no, 
                    vocab_no, 
                    correct 
               FROM vocab_stats 
              WHERE owner = 1111) AS nvs ON mw.no = nvs.vocab_no 
      WHERE (nvs.correct &gt; 0 ) 
        AND mw.level = 1
  </code></pre>
  
  <p>...and:</p>
  
  <pre><code>SELECT * 
    FROM vocab_stats vs, 
         mst_words mw 
   WHERE mw.no = vs.vocab_no 
     AND vs.correct &gt; 0 
     AND mw.level = 1 
     AND vs.owner = 1111
  </code></pre>