That's awesome,

My worst DELETE fail however was:

  DELETE * FROM table WHERE [long condition that resolves to true for all records]

Now i write SELECT or SELECT COUNT(*) over and over again until i see the data i expect and then change it to a DELETE/UPDATE.

It's not my personal habit but some folks I know turn off auto commit and BEGIN a transaction every time they enter an interactive SQL sessions. They then default to ROLLBACK at least once before COMMITing them.

That and having a user with read-only permissions or a read replica