title: How does the dot means in sql when the where clause is different
body: <p>i express me
  i saw recently this piece of code</p>
  
  <pre><code>SELECT a.id a.name FROM department
  </code></pre>
  
  <p>the issue is that 'departement' is a table name.</p>
  
  <p>and 'a' is also a table name which contains id and name fileds.</p>
  
  <p>why we use 2 differnt table name ? it is not the same thing... it's difficult to get brain for me, so explain me.</p>
  
  <p>lower in the code there is a left join, maybe it can have a rapport ?</p>