title: Got error 'repetition-operator operand invalid' from regexp (Error #1139)
body: <p>I have a column <code>phone_number</code> on a database that an entry may contain more than one phone number. The plan is to identify entries which do not pass a regex expression validation.</p>
  
  <p>This is the query I am using to accomplish my objective:</p>
  
  <pre><code> SELECT id, phone_number FROM store WHERE phone_number NOT REGEXP '^\s*\(?(020[78]?\)? ?[1-9][0-9]{2,3} ?[0-9]{4})|(0[1-8][0-9]{3}\)? ?[1-9][0-9]{2} ?[0-9]{3})\s*$';
  </code></pre>
  
  <p>Problem is, every time I run the code, I get an error:</p>
  
  <p><code>Error Code: 1139. Got error 'repetition-operator operand invalid' from regexp</code></p>
  
  <p>Thanks in advance.</p>