Depends on the number of changes which happen per time-unit. Sometimes, you cannot take the database offline, because you would miss many queries, and you might run into some bad problems if you try to just run them on the corrected database later on. So here are your options, imho:
- Make a backup and hot-fix the problem. RISKY, might lead to an unplanned downtime
- Make the changes on a local copy and upload it. Save, but does not work in all situations
- Use the next planned downtime to fix the problem or make a request for a planned downtime. Save and the thing I would do. Come up with a little game or something to pass the time for your users while they cannot access the site, so you will not take a too huge hit on visitor counts