Most SQL bugs aren't logic errors. They're sequence errors — the result of writing a query in one order and the database executing it in another. Consider this query: SELECT department , COUNT ( * ) AS headcount FROM employees WHERE headcount > 5 GROUP BY department ; Enter fullscreen mode Exit fullscreen mode It looks reasonable. It will not run. The error you get back — something like column "headcount" does not exist — feels like a bug in the database. It isn't. The database is being completely consistent. headcount doesn't exist yet when WHERE runs, because SELECT hasn't run yet. You defined the alias in step 5. You tried to use it in step 2. This is the trap: SQL reads like a sentence, so we write it like one. Give me the department and count, from employees, where the count is greater than five . That sentence has a natural English order, and SQL's syntax follows it.…