Joins — Practice Questions
34 free PYSPARK and SQL challenges on Joins, auto-graded in the browser. Each states the problem, shows the input and expected output, and explains the answer.
- Find Customers Missing from New Table — Easy · SQL · +100 XP
- Customers With at Least One Order — Easy · SQL · +50 XP
- Customers Who Have Never Placed an Order — Easy · SQL · +50 XP
- Count Orders Per Customer Including Zero — Easy · SQL · +50 XP
- Total Amount Spent Per Customer (With Zero) — Easy · SQL · +50 XP
- Find Employees in the HR Department — Easy · SQL · +50 XP
- Count Employees Per Department — Easy · SQL · +50 XP
- List All Employees With Department Names — Easy · SQL · +50 XP
- Find Employees NOT in the HR Department — Easy · SQL · +50 XP
- E-commerce: Customers Who Placed an Order (IN Subquery) — Easy · SQL · +50 XP
- E-commerce: Count Orders Per Customer — Easy · SQL · +50 XP
- E-commerce: Customers With No Orders (NOT IN) — Easy · SQL · +50 XP
- Banking: Customer Account Type and Balance — Easy · SQL · +50 XP
- Healthcare: Appointments Per Patient — Easy · SQL · +50 XP
- Healthcare: Total Fees Collected Per Doctor — Easy · SQL · +50 XP
- Retail: Total Amount Spent Per Customer — Easy · SQL · +50 XP
- Logistics: Total Freight Earned Per Driver — Easy · SQL · +50 XP
- Advanced Joins: Customers With No Orders — Easy · SQL · +50 XP
- Orders: List Orders With Customer Names (INNER JOIN) — Easy · SQL · +50 XP
- Customers Who Never Placed an Order — Easy · SQL · +50 XP
- Count Employees Per Department Including Empty Departments — Easy · SQL · +50 XP
- List Departments That Have No Employees — Easy · SQL · +50 XP
- List Every Employee With Their Manager's Name (Self JOIN) — Easy · SQL · +50 XP
- Find Products That Have Never Been Ordered — Easy · SQL · +50 XP
- Inner Join Orders with Customers — Easy · PYSPARK · +50 XP
- HR: Employees With Rating >= 4 in Latest Review — Hard · SQL · +200 XP
- E-commerce: Total Amount Spent Per Customer — Medium · SQL · +100 XP
- Banking: Total Amount Deposited Per Customer — Medium · SQL · +100 XP
- Retail: Most Expensive Product in Each Category — Medium · SQL · +100 XP
- Advanced Joins: All Customers With Orders (Including No Orders) — Medium · SQL · +100 XP
- Advanced Joins: Payments With Order and Customer Info — Medium · SQL · +100 XP
- Bonus: Total Payment Per Customer (3-Table JOIN) — Medium · SQL · +100 XP
- Bonus: Each Order With Customer Name and Payment Amount — Medium · SQL · +100 XP
- Total Sales Amount by Product Category (JOIN) — Medium · SQL · +75 XP