The Three Statements

INSERT adds rows. UPDATE changes them. DELETE removes them.

Name your columns in an INSERT. Relying on column order works until someone adds a column, at which point every insert in the codebase silently writes to the wrong place.

The database is rebuilt from the fixture on every run, so you can experiment freely and press Run again to get a clean table back.

✦ UPDATE and DELETE without WHERE change every row

There is no confirmation and no undo. The habit that prevents it is simple and universal among people who have done this a while: write the WHERE as a SELECT first, look at exactly which rows come back, and only then change the SELECT into an UPDATE or a DELETE.