On the Khan Academy site in the Modifying Databases with SQL section read Make your SQL safer

True or False:

11. You can use transactions when you want to make sure that all of your commands operate on

the same view of the data - when you want to ensure that no other transactions operate on

that same data while the sequence of commands is running.

12. Most companies make backups of their databases - on an hourly, daily, or weekly basis,

depending on the size of the database and space available.

13. Sometimes the data from a backup may be a little outdated, but outdated data is often better

than no data at all.

14. Replication is always storing multiple copies of the databases in different places.

15. Replication is critical for very important data.

16. It is a lot more effort to replicate databases and it often means slower performance since

write operations have to be performed in all of them, so companies must decide whether the

benefits of replication are worth the costs, and investigate the best way of setting it up for

their environment.

17. Many database systems have users and privileges built into them, because they are stored on a server and accessed by multiple users.

18. As a general rule, there should be only a few users that have full access to the database (like

backend engineers), since it can be so dangerous.

19. In a big company, you often don't even want to give SELECT access to most users, because

there might be private data in a table, like a user's email address or name.

20. Many companies have anonymized versions of their databases that they can query on without worrying about access to private information.