title: PHP : display "selected value" by default on selection box
body: <p>I have a <code>select</code> box on my form to search shops in cities.  Suppose that they are City 1, city 2, city 3, etc. When I select City 3 and click search, the data is posted and shops are displayed correctly. but the selection box still shows City 1 as the default value.  It makes the user confused! </p>
  
  <p>If I have searched City 3, after reloading the page, the selection box should display City 3 as "Selected value" and not the first value of selection box.</p>
  
  <p>How do I do it? Please help me.</p>