title: SQL INJECTION and two queries
body: <p>So, I read article about SQL injection and there was an example:</p>
  
  <pre><code>SELECT * FROM table_name WHERE smth = 'x'; 
  UPDATE table_name SET smth ='smth@email.addr' WHERE user = 'admin';
  </code></pre>
  
  <p>Why it doesn't work? Or it is an old article and nowadays this way is nonsense? So how hackers update mysql then?
  Thanks.</p>