title: Round to n Significant Figures in SQL
body: <p>I would like to be able to round a number to n significant figures in SQL. So:</p>
  
  <pre><code>123.456 rounded to 2sf would give 120
  0.00123 rounded to 2sf would give 0.0012
  </code></pre>
  
  <p>I am aware of the ROUND() function, which rounds to n decimal places rather than significant figures.</p>