title: how to do something like this in sqlalchemy?
body: <p>Assuming that:</p>
  
  <pre><code>class Users(db.Model):
      __tablename__ = 'users'
  
      id = db.Column(db.Integer, primary_key=True)
      username = db.Column(db.String)
  </code></pre>
  
  <p>how can i do this in sqlalchemy:</p>
  
  <pre><code>select id,username,0 as deleted from users
  </code></pre>
  
  <p>which <code>deleted</code> is not in <code>users</code>.</p>