title: what is the equivalent of ispostback(.NET) in PHP?
body: <p>I just start coding in PHP, 
  i wrote my first <strong>php + mysql</strong> program for inserting data through web form. it works fine, but whenever i refresh the page, it automatically saves null record to my database.
  i know the solution in .NET is ispostback, but not in php? 
  can somebody give me some idea in PHP.</p>
  
  <p><strong>Code is here:</strong></p>
  
  <pre><code>&lt;body&gt;
  &lt;form action="mySQLTest.php" method="post"&gt;
  First Name :&lt;input type="text" name ="txtFirstName"/&gt; &lt;br/&gt;
  Last Name: &lt;input type="text" name ="txtLastName"/&gt;   &lt;br/&gt;
  Age : &lt;input type="text" name= "txtAge" /&gt; &lt;br/&gt;
  &lt;input type="submit"/&gt;
  &lt;/form&gt;
  &lt;?php
     $con = mysql_connect("localhost","root","");
     if(!$con)
     {
      die('Could not Connect:' .mysql_error());
     }
  
     mysql_select_db("test", $con);
  
     if($_REQUEST[])
     {
  
     $sql1 = "Insert into info(FirstName, LastName, Age) Values('$_POST[txtFirstName]','$_POST[txtLastName]','$_POST[txtAge]')";
     }
     if(!mysql_query($sql1, $con))
     {
      die('Error: '.mysql_error());
     }
     else                                
     {
     echo "1 Record Added";
     }
  
     mysql_close($con)
  ?&gt;
  &lt;/body&gt;
  </code></pre>