title: relation does not exist in postgreSQL but already exist
body: <p>I've read a lot of articles about my problem but no one solve it. So u can see my code here</p>
  <pre><code>DATABASE_URL = os.environ.get('url_of_my_db')
  con = None
  try:
      con = psycopg2.connect(DATABASE_URL)
      cur = con.cursor()
      
      print('PostgreSQL database version:')
      #cur.execute('SELECT version()')
      #cur.execute('SELECT * FROM qwerty')
      
      #cur.execute(sql.SQL('SELECT * FROM {}').format(sql.Identifier('qwerty')))
      #cur.execute(sql.SQL(&quot;INSERT INTO {} (chat_id, username, created_on) VALUES (8985972942, vovakirdan, 2022-01-05)&quot;).format(sql.Identifier('users')))
      cur.execute(&quot;&quot;&quot;INSERT INTO users (chat_id, username, created_on)
                      VALUES (3131,
                      vovakirdan,
                      2022-01-05)&quot;&quot;&quot;)
      
  
      # display the PostgreSQL database server version
      db_version = cur.fetchone()
      print(db_version)
         
       # close the communication with the HerokuPostgres
      cur.close()
  except Exception as error:
      print('Cause: {}'.format(error))
  
  finally:
      # close the communication with the database server by calling the close()
      if con is not None:
          con.close()
          print('Database connection closed.')
  </code></pre>
  <p>and in my DB table named &quot;users&quot; (named without quotes) are exist, but I still have this error:
  <a href="https://i.stack.imgur.com/ef64B.png" rel="nofollow noreferrer">error</a></p>
  <p>...relation &quot;users&quot; does not exist</p>
  <p>all the #commented code doesn't work and send the same error besides SELECT version(), it works perfectly that proves that connection works.</p>