UPDATE wp_posts SET `post_content` = REPLACE (`post_content`, 'src="http://www.your-site.com', 'src="https://www.your-site.com');
UPDATE wp_2_posts SET `post_content` = REPLACE (`post_content`, 'src="http://www.your-site.com', 'src="https://www.your-site.com');
UPDATE wp_posts SET `guid` = REPLACE (`guid`, 'http://www.your-site.com', 'https://www.your-site.com') WHERE post_type = 'attachment';
UPDATE wp_2_posts SET `guid` = REPLACE (`guid`, 'http://www.your-site.com', 'https://www.your-site.com') WHERE post_type = 'attachment';
https://premium.wpmudev.org/blog/replacing-image-links/?utm_expid=3606929-106.UePdqd0XSL687behGg-9FA.0