title: Why we should use QUOTENAME function?
body: <p>I get acquainted with <a href="https://msdn.microsoft.com/en-us/library/ms176114.aspx" rel="nofollow">QUOTENAME</a> function. But I don't understand for what I can use it? Why it is so widely used?</p>
  
  <pre><code>select quotename('[abc]') -- '[[abc]]]'
  select quotename('abc') -- '[abc]'
  select '[' + 'abc' +']'  -- why it is not so good as previous?
  </code></pre>