The PHP script can access the database, then send a query which will save the data into the database. PHP has built-in functions to handle these tasks.

You can find reference material on the topic here: [us2.php.net...]

Here's some stripped-down, simple code:

# open a connection to the database
@ $db = mysql_pconnect("localhost", "username", "password");
mysql_select_db("databasename");

# send a query
$query = "INSERT INTO 'tablename' ('ID','FIELD1','FIELD2') VALUES ('','".addslashes($somedata)."','".addslashes($someotherdata)."');
$result = mysql_query($query);
if (!$result) { echo mysql_error();}

• Basics of Submitting and Emailing Forms with PHP [webmasterworld.com]
  
• Commonly used MySQL Commands [webmasterworld.com]
  
• SQL Injection Vulnerability [webmasterworld.com]<--make sure to escape everything with mysql_real_escape_string [us3.php.net] for queries
  

Good luck!