title: postgres: how to create role with insert and update access
body: <p>I have a user <code>db_owner</code> who is owner to my database called 'Sales'.</p>
  <p>Now i have to create two groups(<code>sales_ro</code> and <code>sales_riu</code>) and then i will add users to this groups.</p>
  <p><code>sales_ro</code> group should inherit(from <code>db_owner</code>) read access on tables and execute on functions  in Sales db</p>
  <p><code>sales_riu</code> group should inherit(from <code>db_owner</code>) insert and update access on tables and execute on functions  in Sales db.</p>
  <p>can we create such two groups in Postgres ?</p>