Customers Who Never Ordered
Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.
Practice this as a mock interviewFree to start, no account neededProblem
Marketing wants to email everyone who signed up and never bought anything.
Table customers:
id INTEGER primary key
name TEXT
Table orders:
id INTEGER primary key
customer_id INTEGER the customer who placed it; may be NULL for a guest checkout
total REAL
Return the name of every customer with no orders.
Columns: name.
Order by name, ascending.
Examples
Constraints
- A guest order has customer_id NULL and belongs to nobody.
What the interviewer grades
A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.