title: Get only digits using regexp
body: <p>I have in table column <code>pnum_s</code></p>
  
  <p>I need get only that rows, which value in column <code>pnum_s</code> is exactly 10 symbol and all these symbols are only digits</p>
  
  <p>what query must write for this?</p>
  
  <p>I am trying </p>
  
  <p><code>SELECT * FROM mytable WHERE pnum_s REGEXP '^\d+$'</code></p>
  
  <p>But this not returns 0 rows</p>