friend.php

<?php
$dry_run = false;

// http://php.net/manual/ref.pdo-mysql.connection.php
$pdo_dsn  = 'mysql:xxx';
$pdo_user = 'xxx';
$pdo_pass = 'xxx';

$dbh = new PDO($pdo_dsn, $pdo_user, $pdo_pass);
$sth = $dbh->query('SELECT id FROM member WHERE is_active = 1 AND is_login_rejected = 0 ORDER BY id');
$ids = $sth->fetchAll(PDO::FETCH_COLUMN);

$results = array();
$max_id = max($ids);

foreach ($ids as $i) {
    for ($j = $i + 1; $j <= $max_id; $j++) {
        if (!in_array($j, $ids)) continue;

        $results[] = sprintf('(%d,%d,1,0)', $i, $j);
        $results[] = sprintf('(%d,%d,1,0)', $j, $i);
    }
}

$query1 = 'TRUNCATE TABLE member_relationship';
$query2 = 'INSERT INTO member_relationship(member_id_to,member_id_from,is_friend,is_friend_pre) VALUES ' . implode(',', $results);

if ($dry_run) {
    echo $query1, ';', PHP_EOL;
    echo $query2, ';', PHP_EOL;
} else {
    $dbh->query($query1);
    $dbh->query($query2);
}