When Should You Alter a Database Table Instead of Recreating It?

In modern databases, adding a new column with a nullable option is usually safe. It's a common practice, and unless you're doing something drastic, you shouldn't run into major problems. Just keep in mind that before making changes, you should always consider how existing data will be affected.

To build on what's been said: it really comes down to your specific project. Always make sure that your data representation in the live database is accurate before applying changes. Testing things out in a controlled environment can save you from surprises. It's essential to create a solid script to automate the changes, and make sure you back up your data before trying major updates. Common mistakes include forgetting to keep old data or failing to consider data that’s being accessed while you update.

For most projects, altering the existing table is the easiest route. Changes like adding or altering columns happen pretty frequently, and it requires less work compared to creating a new table and migrating data. Of course, there are rare cases where a new table might be justified, but that's something you’d likely see only a few times throughout your career. It's more common during the initial development phases than in the maintenance of a mature system.

And definitely think through all the implications of your changes before committing. It's worth the time to ensure that you won’t run into unexpected issues later on, especially in a production environment.

It really depends on how significant the change is. If you're just adding a column, that's usually straightforward—just add it as nullable at first, especially since there's likely existing data. If the change requires more fundamental shifts in how the data is structured or if new business logic is being introduced that the current schema can't handle, then rebuilding the table might be necessary. Just be aware that this can lead to much bigger headaches down the line, especially with existing code that has to be adapted—sometimes it's even better to just start fresh with new code rather than force the old one to fit the new schema.