Window Functions: SQL's Most Powerful Feature Nobody Uses
You are going to hit a problem. Not now. A few weeks into data analysis work, or maybe during a job interview, someone will ask you something like: "For each sale, can you show the sale amount alongside the running total for that salesperson?" Or: "Rank employees by salary within each department without removing any rows." Or: "For each order, show the previous order's amount for comparison." You will try GROUP BY. It collapses rows. Wrong. You will try joins. Awkward, multiple CTEs. Messy. You
Comment
Sign in to join the discussion.
Loading comments…