Ajax implementation of the number of clicks plus 1 code instances

Ajax implementation of the number of clicks plus 1 code examples:
In the chapter on clicking a button to implement a code example that shows how to click a button to achieve a number plus 1, but it seems that there is no practical use, the following share a relatively complete code that can be used in practical applications, this code is AJAX in conjunction with PHP code implementation.
One. The AJAX code is as follows:

<! DOCTYPE html>
Two. PHP Code:
<?php  mysql_connect (' localhost ', ' root ', ');  Mysql_selectdb (' click ');  $rs =mysql_query ("UPDATE click SET num = num +1 WHERE name = '". $_get[' a ']. "'");  if (Mysql_affected_rows () ==1) {    $rs =mysql_query ("SELECT * from click where Name= '". $_get[' a ']. "'");    $row =mysql_fetch_array ($rs);    echo $row [' num '];  }? >
Ajax implementation of the number of clicks plus 1 code instances