title: SQL Select statement - multiple tables allow null values
body: <p>I do realise that problem I am facing is not a rocket science but still, I did not find any information about fixing this.</p>
  
  <p>I have multiple tables in my database (<code>PSQL</code>) I want to create a <code>select</code> query to make a reporting function for my app.</p>
  
  <p>Here is my query:</p>
  
  <pre><code>select 
      s.id, s.name, st.name, p.firstname || ' ' || p.lastname, 
      f.name, f.store_date, bdt.name, bd.comment 
  from  
      system s, systemstatus st, role w, person p, file f, 
      documenttype bdt, document bd 
  where 
      w.system_id = s.id and 
      p.id = w.person_id and 
      st.id = s.status_id and 
      bd.system_id = s.id and 
      bd.file_id = f.id and 
      bd.type_id = bdt.id and 
      bd.role_id = w.id;
  </code></pre>
  
  <p>Query works I get <code>300</code> rows fully filled with values I am searching for. Problem is that I have about <code>1000</code> rows in <code>System</code> Table. It is possible that there is no <code>Person</code> or <code>Document</code> which could be linked with particular <code>System</code>.</p>
  
  <p>I would like to see all rows that are in my <code>System</code> table (I mean about 1000), and when I can't link <code>Person</code> or <code>Document</code> with <code>System</code> I want the field to be null ( now it is not shown at all)</p>