Every query that you run on a SQL database that modifies data in some way, has the potential of causing damage if it has not been written correctly.
Luckily for us, there are a few commands that can be used in order to help prevent this type of user error.
BEGIN TRANSACTION - Run this before running your query.
COMMIT TRANSACTION - Run this after running your query, only if it was successful and did what you wanted it to.
ROLLBACK TRANSACTION - Run this is your query did something nasty.