title: Replacing Pandas Dataframe output from NoneType to 0
body: <p>Output of a SQL query that I am storing in a dataframe is of <code>NoneType</code>.</p>
  
  <p>How could I replace this to <code>0</code></p>
  
  <pre><code>db_conn.execute(f"""select count (*) from table""")
  output = db_conn.fetchone()[0]
  </code></pre>