title: How does select work in postgresql, postgis?
body: <p>I have the following statement in a book:</p>
  
  <pre><code>SELECT AddGeometryColumn('public','my_geometries','my_points',-1,'POINT',2);
  INSERT INTO my_geometries (name,my_points) 
  VALUES ('Home',ST_GeomFromText('POINT(0 0)')); 
  </code></pre>
  
  <p>I understand the insert into, values part but the first statement is a bit unclear. In the book they say they're creating a new point by using the SELECT statement.</p>
  
  <p>So how can this work? </p>
  
  <pre><code>SELECT AddGeometryColumn('public','my_geometries','my_points',-1,'POINT',2);
  </code></pre>
  
  <p>By looking at the api <a href="http://postgis.refractions.net/docs/AddGeometryColumn.html" rel="nofollow">http://postgis.refractions.net/docs/AddGeometryColumn.html</a> it seems it adds a new column but how does the select work since that object isn't created? How can it select?</p>