SQL: UPDATE and DELETE without WHERE hit every row

There is no confirmation prompt and no undo outside a transaction. The habit that prevents it is writing the statement as a SELECT first, then editing it in place.

Code

-- 1. See what you are about to change
SELECT * FROM users WHERE id = 42;

-- 2. Turn it into the UPDATE, keeping the same WHERE
UPDATE users SET email = 'new@x.com' WHERE id = 42;

-- Or make it recoverable:
BEGIN;
UPDATE users SET email = 'new@x.com' WHERE id = 42;
SELECT COUNT(*) FROM users WHERE email = 'new@x.com';   -- expect 1
COMMIT;   -- or ROLLBACK

Output

UPDATE 1        <- what you wanted
UPDATE 812445   <- the WHERE was missing

-- MySQL's client has a guard for exactly this:
--   mysql --safe-updates
-- It refuses an UPDATE or DELETE with no key in the WHERE clause.

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Published 2026-08-25