[Slide]

db.php
<?php

$link_id = mysql_pconnect($server, $username, $password);
mysql_select_db($link_id, $db);

?>

page.php
<?php

require_once("db.php");

$results = mysql_query($sql, $link_id);

?>

Quick and dirty, you should make a db class to do this, and build in input cleaning functionality etc into it.

Edit: At work now, here's my db class. Username etc are hard coded, easy enough to change that.

  class db {
    
    private $linkId;
    private $preparedQuery;
    private $resultId;
    
    function __construct() {
      $this->linkId = mysql_pconnect("localhost", "support", "password");
      mysql_selectdb("support", $this->linkId);
      $this->preparedQuery = "";
    }
    
    private function clean_input($string) {
      return mysql_real_escape_string($string, $this->linkId);
    }

    function prepare($sql_query, $values = "") {
      if (is_array($values)) {
        foreach ($values as $key => $value) {
          $safe_value = $this->clean_input($value);
          $sql_query = str_replace($key, $safe_value, $sql_query);
        }
        $this->preparedQuery = $sql_query;
      } else {
        $this->preparedQuery = $sql_query;
      }
    }
    
    function execute($debug = FALSE) {
      if ($this->preparedQuery) {
        if ($debug == TRUE) {
          echo $this->preparedQuery;
        }
        $this->resultId = mysql_query($this->preparedQuery, $this->linkId);
        if ($this->resultId) {
          return $this->resultId;
        } else {
          return false;
        }
      } else {
        return false;
      }
    }
    
    function error() {
      echo mysql_error($this->linkId);
    }
    
    function num_rows($resultId = "") {
      if ($resultId) {
        return mysql_num_rows($resultId);
      } else {
        return mysql_num_rows($this->resultId);
      }      
    }

    function fetch_assoc($resultId = "") {
      if ($resultId) {
        return mysql_fetch_assoc($resultId);
      } else {
        return mysql_fetch_assoc($this->resultId);
      }
    }
  
  }

  $db = new db();
  $sql_query = "SELECT * FROM foo WHERE var=&param";
  $sql_param = array("&param"=>"blah");
  $db->prepare($sql_query, $sql_param);
  $result = $db->execute();