Almost anyone who has spent time working with SQL made — or had to fix — this kind of bug:
-- two tables (sketch) -- users {id, user_name} trans {id, amt, cur, tx_time, user_id}
-- query with a typo -- SELECT user_name , tx_time , amt , cur FROM users as u JOIN trans as t ON u.id = t.id -- <- typo !! WHERE user_name = 'jack' ;
Try the query, here is the DDL with some data; note the wrong result. Continue reading "Types and Typos in SQL [1]"