title: QGIS & PostGIS (map points(lat and long with raduis on USA map)
body: <p>I installed QGIS and PostGIS.  I have 200 points that I want to display with a radius of 100 miles on a graph of the US.  </p>
  
  <p>I have imported my latitude and longitude in the PostGIS database. So I have three fields: [address], [lat], [lng].</p>
  
  <p>1) Do I need to convert the lat and lng fields into a point or geom field? If so how? (st_buffer?)
  2) What command/SQL do I use to display the points with radius?</p>
  
  <p>I can query my points like so.. </p>
  
  <p><code>SELECT * FROM postgis_test</code></p>
  
  <p>I just don't understand how to display all the points on a map with the radius.</p>
  
  <p>Example points:</p>
  
  <pre><code>city        lat          lng
  New York    40.7127753  -74.0059728
  Los Angeles 34.0522342  -118.2436849
  Chicago     41.8781136  -87.6297982
  </code></pre>