For performance reasons you often will wish to separate data into multiple databases so that locks on one table do no affect other operations. However at one point or another you'll want to use data between the various databases. Fortunately SQLite allows for such an operation, allowing for linking of multiple databases.

<?php
chdir(dirname(__FILE__)); // pres2 hack
$ip_int = sprintf("%u", ip2long("24.100.195.79"));

$db = sqlite_open("./ip.db");

// attach to another database
sqlite_query("ATTACH DATABASE './flag.db' AS 'flags'", $db);

$data = sqlite_array_query($db, "
SELECT country_name, flag_file
FROM ip_ranges ir 
INNER JOIN country_data cd ON ir.country_code=cd.id
INNER JOIN flags.flag_db f ON f.country_id=cd.id
WHERE {$ip_int} BETWEEN ip_start AND ip_end",
SQLITE_ASSOC);

// detach from attached database
sqlite_query("DETACH DATABASE flags", $db);

echo "User is located in {$data[0]['country_name']}";

// pres2 hackery
$path = dirname($_SERVER['PHP_SELF']). "/../../presentations/slides/sqlite/";

echo " <img src='{$path}{$data[0]['flag_file']}' />";
?>
Output