title: sqlalchemy NoSuchTableError when table exists in database
body: <p>I am using PostgreSQL+Psycopg2, SQLAlchemy. I've already created my database "new_db" using pgAdminIII tool and a new schema in it as "new_db_schema". Under this schema I've all the tables I need. My code looks like this.</p>
  
  <pre><code>from sqlalchemy import create_engine
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import sessionmaker
  from sqlalchemy import Column, String, Integer, Boolean
  
  engine_text = 'postgresql+psycopg2://root:12345@localhost:5432/db_name'
  database_engine = create_engine(engine_text, echo = True)
  
  Base = declarative_base(database_engine)
  
  class Some_table(Base):
      __tablename__ = 'some_table' # This table exist in database.
      __table_args__ = {'autoload':True}
  
      col1 = Column(String, primary_key=True)
      col2 = Column(Boolean)
  
      def __init__(self, col1_name, col2_name):
          self.col1 = col1_name
          self.col2 = col2_name
  
  if __name__ == "__main__":
      a = Some_table('blah', 'blah')
  </code></pre>
  
  <p>Now when i try to run the following code, I get <code>sqlalchemy.exc.NoSuchTableError: some_table</code>.</p>
  
  <p>Since I already have the database setup with all the tables, I would like to autoload while creating classes. Am I missing something here? I need to write such classes for all the tables present in the database. Any help would be greatly appreciated.</p>
  
  <p>Thanks</p>