title: difference between "tab" table and all_tables in oracle
body: <p>what tables are returned by using (in oracle)</p>
  
  <pre><code>select * from tab
  </code></pre>
  
  <p>and</p>
  
  <pre><code>select * from all_tables
  </code></pre>
  
  <p>I would like to know the difference between two.</p>