title: What's the purpose of SQL keyword "AS"?
body: <p>You can set table aliases in SQL typing the identifier right after the table name.</p>
  
  <pre><code>SELECT * FROM table t1;
  </code></pre>
  
  <p>You can even use the keyword <code>AS</code> to indicate the alias.</p>
  
  <pre><code>SELECT * FROM table AS t1;
  </code></pre>
  
  <p>What's the difference between them if any?</p>
  
  <p>I see old DBA people tend to write statements without <code>AS</code>, but most of the new tutorials use it.</p>
  
  <p><em>Update:</em> I know what's the purpose of table and column aliases. I'm curious, what's the reason of having a separate keyword for setting aliases while it works without it as well.</p>