title: Replace character if not preceeded by same character
body: <p>I'm trying to escape some backslash's by replacing a single <code>\</code> with <code>\\</code>:</p>
  <pre><code>UPDATE Table
  SET Column = REPLACE(Column , '\', '\\')
  </code></pre>
  <p>But I would like to do the replace only if the backslash is not precedent by another backslash, so that input <code>test\</code> should replace to <code>test\\</code> but <code>test\\</code> should stay <code>test\\</code>.</p>
  <p>If more than two backslash are present it shouldn't replace either.</p>