### tl;dr

# UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, '', '')

# Update self-hosted embeds (images, iframes, scripts, etc.)
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://yoursite.com', 'https://yoursite.com');
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://www.yoursite.com', 'https://www.yoursite.com');

# Update internal pingbacks
UPDATE `wp_comments` SET `comment_author_url` = REPLACE(comment_author_url, 'http://yoursite.com', 'https://yoursite.com');
UPDATE `wp_comments` SET `comment_author_url` = REPLACE(comment_author_url, 'http://www.yoursite.com', 'https://www.yoursite.com');

# Update YouTube embeds
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://www.youtube.com', 'https://www.youtube.com');
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://img.youtube.com', 'https://img.youtube.com');

# Update Vimeo embeds
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://player.vimeo.com/', 'https://player.vimeo.com/');

# Update Slideshare embeds
UPDATE `wp_posts` SET `post_content` = REPLACE(post_content, 'http://www.slideshare.net', 'https://www.slideshare.net');

Why?

How

Find all posts linking to insecure URLs

SELECT * FROM `wp_posts` where `post_content` LIKE "%http://%"

While you might be tempted to just update ALL links in posts to https in one go with the above command, this can cause issues. Not all sites (unfortunately) have shifted to https yet and if you update all posts links, you’ll get plenty of broken ones. Best approach is to update the links for known sites that you know for a fact use https (Sites like YouTube, Vimeo, Twitter as well your own site)

This means anything in the wp-content/uploads directory

# Update Media links
UPDATE `wp_posts` SET `post_content`=REPLACE(post_content, 'http://amiranzur.com/wp-content/uploads', 'https://amiranzur.com/wp-content/uploads')

Update video emeds

# Update YouTube links
UPDATE `wp_posts` SET `post_content`=REPLACE(post_content, 'http://youtube.com/', 'https://youtube.com/')

# Update Vimeo links
UPDATE `wp_posts` SET `post_content`=REPLACE(post_content, 'http://player.vimeo.com/', 'https://player.vimeo.com/')