title: connecting to database using sqlalchemy using DATABASE_URL
body: <p>I am comfortable in using SQL query languages and need to develop a web application.
  I am learning python -sqlachemy and stuck in get connected to postgressql database.</p>
  <p>Please let me know:
  what are the libraries i need to install ?
  How do i Configure DATABASE_URL in flask.[enter image description here][1]</p>
  <p>I am stuck with code line no-6.
  I need to know how to get DATABASE_URL configured? I am very new potgressql.
  [1]: <a href="https://i.stack.imgur.com/7oGRC.png" rel="nofollow noreferrer">https://i.stack.imgur.com/7oGRC.png</a></p>