Where should you start?
Six questions on a practice marketplace’s data. Each answer is worked out from the table on screen, so there’s nothing to guess from the wording.
About 4 minutes. It stops at the first question that doesn’t land and shows what you already do.
How many different customers have at least one paid order?
order_id | customer | status |
|---|---|---|
| 101 | Anna | paid |
| 102 | Leon | cancelled |
| 103 | Anna | paid |
| 104 | Nina | pending |
| 105 | Leon | paid |
Where it can lead
- Start, day 1 · SQL from zero
- Case 1 · the case round
- Wrong Number · what a number counts