Best answer
I agree with Allen, perform a database dump, and then do the search/replace on that dump and re-import.
So to dump MySQL (assuming linux) lets go ahead and make two, one we're going to mess with, the other is a backup incase something goes wrong.
Code:
mysqldump -u username -P database_name -> /path/to/dump/file.sql
mysqldump -u username -P database_name -> /path/to/dump/full_backup.sql
Next you can use sed to search and replace.
Code:
sed -i 's/http:\/\//https:\/\//g' /path/to/dump/file.sql
Finally, re-import the database.
Code:
mysql -u username -P databae_name < /path/to/dump/file.sql
That autta do the trick. I you run into any issues lemme know but always take backups first