wp-redirect.php

<?php
// Check if a redirect is needed
$redirect = !isset($_SERVER['HTTPS']) || ('on' != $_SERVER['HTTPS']);
$redirect = $redirect || !isset($_SERVER['HTTP_X_FORWARDED_PROTO']) || ('https' != $_SERVER['HTTP_X_FORWARDED_PROTO']);

// Permanent redirect to https version
if ($redirect) {
    header('Location: https://' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'], true, 301);
    exit();
}

wp-update-2https.sql

UPDATE tableprefix_posts
SET 
post_content = REPLACE(post_content, 'http://www.midominio.com', 'https://www.midominio.com'),
post_excerpt = REPLACE(post_content, 'http://www.midominio.com', 'https://www.midominio.com')
WHERE post_content LIKE '%http://www.midominio.com%' OR post_excerpt LIKE '%http://www.midominio.com%'