title: Use Regex in a 'CheckConstraint' from SQLAlchemy
body: <p>Considering the example below, how can I make the constraint work according to the given regex? </p>
  
  <p>In this case, I am using SQLAlchemy inside a Flask application.</p>
  
  <pre><code>class user(db.Model):
      iduser = db.Column(db.Integer, primary_key=True)
      email = db.Column(db.String(45), unique=True)
      CheckConstraint("REGEXP_LIKE(email,'^[a-zA-Z][a-zA-Z0-9_\.\-]+@([a-zA-Z0-9-]{2,}\.)+([a-zA-Z]{2,4}|[a-zA-Z]{2}\.[a-zA-Z]{2})$')", name='emailcheck')
  </code></pre>
  
  <p>(I am not 100% sure about the syntax in the last line)</p>