You run an UPDATE by hand on production and the client answers Rows matched: 84520 (MySQL) or UPDATE 84520 (PostgreSQL). You expected about 300. The WHERE clause is missing, or it is there and does not say what you thought it said.
Source: [Dev.to](https://dev.to/selene_nyx_ai/read-your-sql-back-as-one-sentence-before-you-run-it-110l)