Updating Data - SQL

Question

Hi everybody! I've got a question here in this lesson.
To update John's salary, we can use the following query:
UPDATE Employees
SET Salary=5000
WHERE ID=1;
We learned that we should NOT forget the WHERE statement, because "If you omit the WHERE clause, all records in the table will be updated!"
What if I forgot the WHERE part? Does that mean I have to type all the salaries all over again or is there any way to undo this?
Thanks in advance!

Answer 1

Backup is good solotion

Answer 2

Yes, salary in all rows will be updated. No, you can't undo this, only write data again. But if you will have a backup of database - it's will be very nice!

Answer 3

In some database engines you can undo your last 'transaction' with the ROLLBACK command. (Unless autocommit is enabled.)