title: Oracle columns definition varchar(1) M (male) or F (female)
body: <p>I´m working with Oracle sql developer</p>
  
  <p>I need to define a constraint for this column of a new data base:
  <code>event_gender VARCHAR2(1)</code> 
  It should accept 1 character: <code>M</code> (male) or <code>F</code> (female);  null not allowed</p>
  
  <p>I defined the constraint in this way but doesn´t work:</p>
  
  <pre><code> CONSTRAINT "Check_gender" CHECK (REGEXP_LIKE(event_gender,'M'||'F'))
  </code></pre>
  
  <p>Any suggestion?</p>