title: Dynamic population of drop down list in html and php
body: <p>I am working on student attendance system project
  for that i am using html and php 
  I need the solution for this problem</p>
  
  <p>i have 4 drop down list 
  In the <code>first drop down list</code> contains <strong>Civil Engg,Comp Engg etc.....and so on</strong>.
  In the <code>second dropdown list</code> subject names are there that are stored in mssql database and depending on the value selected in first drop down I need to populate the subject from the database
  like </p>
  
  <pre><code>select * from allsubjects where branch='civilengg';
  </code></pre>
  
  <p>so please any give me the solution for this scenario</p>