title: how can I know what tables queried in my select sql?
body: <p>I want to get whole table names from an existing selecting sql. <br>
  for example.my select sql is <br></p>
  
  <pre><code>select * from hello h . 
  </code></pre>
  
  <p>how can I get what tables queried in the sql? <br>
  you can only add extra str connecting the select sql, like "explain".<br>
  <img src="https://i.stack.imgur.com/Dr89C.jpg" alt="enter image description here"></p>