title: mysql custom sorting first alpha then numeric using case when
body: <p>How can you sort a query using ORDER BY CASE WHEN REGEXP? or other alternatives?
  I don't want to use UNION. Thank you</p>
  
  <pre><code>mysql&gt; SELECT `floor_id`, `floor_number` FROM `floors`;
  +----------+--------------+
  | floor_id | floor_number |
  +----------+--------------+
  |        1 | 4            |
  |        2 | 7            |
  |        3 | G            |
  |        4 | 19           |
  |        5 | B            |
  |        6 | 3            |
  |        7 | A            |
  +----------+--------------+
  
  
  Expected result:
  +----------+--------------+
  | floor_id | floor_number |
  +----------+--------------+
  |        7 | A            |
  |        5 | B            |
  |        3 | G            |
  |        6 | 3            |
  |        1 | 4            |
  |        2 | 7            |
  |        4 | 19           |
  +----------+--------------+
  </code></pre>