In the past, my hosting server supports UTF-8 URL, I can use the chinese name as Slug in wordpress. In the past few days, there is a server upgrade, then UTF-8 does not support anymore. In the past, because I am lazy, blogging in my top priority, I left the chinese name in URL. I know that is not good for SEO. Also, it made all post links are not working anymore.
I found only way is to reset all post slugs with a random number. I know that affects SEO, it made all post links in search engine in not working.
At the end I ran this sql to reset all old posts,
update set wp_posts
set post_name = floor(RAND()*10)+15
where post_name like '%\%%'

That is a bad solution, but that is the best solution I had now. Now, I manually write 301 Direct for all popular posts I have aware to the new url.

You can access the database via WordPress. You can use any raw SQL too. That is quite easy. You only need to call a global object;
global $wpdb;
For the raw SQL, you can use query method:
$wpdb->query(
"
UPDATE $wpdb->posts
SET post_parent = 10
WHERE ID = 15

"
);

For get the record set,
$drafts = $wpdb->get_results(
"
SELECT *
FROM $wpdb->posts
WHERE post_status = 'draft'
AND post_author =1
"
);

There are insert, update and delete method too.
Please read WordPress development documentation for the further information