SELECT
Beginner
Select All Employees
Write a query to select all columns from the employees table. Return columns: id, first_name, last_name, email, department_id, salary, hire_date, manager_id.
10 XPSolve challenge
Interactive SQL practice
300 SQL Challenges & Exercises
Practice SQL online with 300 interactive challenges built around realistic data. Start with 92 free exercises, get instant feedback, and progress from SELECT basics to Advanced SQL.
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Start by writing a real SQL query
Open the schema, inspect the sample data, run your answer, and see the result immediately.
300 SQL challenges
Open Practice ArenaSELECT
Beginner
Select Employee Names
Write a query to retrieve only the first_name and last_name of all employees. Return columns: first_name, last_name.
10 XPSolve challenge
WHERE
Beginner
Filter High Earners
Find employees with a salary greater than 80,000 and show id, first_name, last_name, and salary. Return columns: id, first_name, last_name, salary.
10 XPSolve challenge
WHERE
Beginner
Engineering Department Employees
Find all employees in department_id = 1 (Engineering), showing their name and salary. Return columns: first_name, last_name, salary.
10 XPSolve challenge
ORDER BY
Beginner
Sort Employees by Salary
List all employees ordered by salary from highest to lowest. Return columns: first_name, last_name, salary. Order results by: salary DESC.
10 XPSolve challenge
GROUP BY
Beginner
Count Employees Per Department
Count the number of employees in each department. Return columns: department_id, employee_count. Order results by: department_id.
10 XPSolve challenge
Aggregations
Beginner
Average Salary by Department
Calculate the average salary for each department. Return columns: department_id, avg_salary. Order results by: department_id.
10 XPSolve challenge
WHERE
Beginner
Find Employees Without Managers
Find all employees who do not have a manager (manager_id is NULL). Return columns: id, first_name, last_name.
10 XPSolve challenge
Aggregations
Beginner
Completed Orders Count
Count how many orders have the status 'completed'. Return columns: completed_count.
10 XPSolve challenge
ORDER BY
Beginner
Most Expensive Products
List the top 3 most expensive products with their names and prices. Return columns: name, price. Order results by: price DESC.
10 XPSolve challenge
INNER JOIN
Intermediate
Employee Department Names
List each employee's full name alongside their department name. Use INNER JOIN. Return columns: first_name, last_name, department_name.
25 XPSolve challenge
HAVING
Intermediate
Departments with High Average Salary
Find departments where the average salary is greater than 75,000. Return columns: department_id, avg_salary. Order results by: department_id.
25 XPSolve challenge
LEFT JOIN
Intermediate
Customers Without Orders
Find all customers who have never placed an order. Return columns: id, name, email.
25 XPSolve challenge
INNER JOIN
Intermediate
Revenue Per Customer
Calculate total revenue (sum of total_amount) per customer, showing customer name and total revenue, sorted by revenue descending. Return columns: customer_name, total_revenue. Order results by: total_revenue DESC.
25 XPSolve challenge
Subqueries
Intermediate
Employees Above Department Average
Find employees whose salary is higher than the average salary of their department. Return columns: first_name, last_name, salary, department_id.
25 XPSolve challenge
INNER JOIN
Intermediate
Product Sales Summary
For each product, show the total quantity sold and total revenue from order_items. Include product name. Return columns: product_name, total_quantity, total_revenue. Order results by: total_revenue DESC.
25 XPSolve challenge
Date Functions
Intermediate
Employee Hire Year Count
Count how many employees were hired in each year, ordered by year ascending. Return columns: hire_year, employee_count. Order results by: hire_year ASC.
25 XPSolve challenge
String Functions
Intermediate
Employee Full Name Concatenation
Create a full_name column by concatenating first_name and last_name with a space between them. Return columns: full_name, email.
25 XPSolve challenge
Window Functions
Advanced
Rank Employees by Salary
Rank employees by salary within each department using RANK(), then return each employee's department, salary, and position. Return columns: first_name, last_name, department_id, salary, salary_rank. Order results by: department_id, salary_rank.
50 XPSolve challenge
Window Functions
Advanced
Running Total of Orders
Calculate a chronological running total of order amounts and return every order with its date, amount, and cumulative revenue. Return columns: id, order_date, total_amount, running_total. Order results by: order_date.
50 XPSolve challenge
CTE
Advanced
Top Earner Per Department (CTE)
Using a CTE, find the highest-paid employee in each department. Return columns: department_id, first_name, last_name, max_salary. Order results by: e.department_id.
50 XPSolve challenge
Window Functions
Advanced
PRO
Month-over-Month Order Growth
Summarize monthly order volume and revenue, then compare each month with the previous month using LAG(). Return columns: month, orders, revenue, prev_revenue, revenue_change. Order results by: month.
50 XPSolve challenge
Window Functions
Advanced
PRO
NTILE Salary Quartiles
Divide employees into four salary quartiles with NTILE(4), then return each employee's name, salary, and quartile. Return columns: first_name, salary, quartile. Order results by: salary DESC.
50 XPSolve challenge
LEFT JOIN
Expert
PRO
Employee Manager Lookup
Use a self LEFT JOIN to list every employee with their direct manager's first name. Return columns: id, first_name, manager_name. Order results by: e.id.
100 XPSolve challenge
CTE
Expert
PRO
Customer Cohort Retention
Calculate how many customers from each acquisition month (cohort) placed orders in their first month. Return columns: cohort_month, cohort_size, first_month_orders, retention_rate. Order results by: c.cohort_month.
100 XPSolve challenge
WHERE
Beginner
Employees in a Salary Range
List employee names and salaries between 70,000 and 90,000, ordered by salary. Return columns: first_name, last_name, salary. Order results by: salary.
10 XPSolve challenge
ORDER BY
Beginner
Alphabetical Employee Directory
Show employee last names, first names, and emails alphabetically by last name. Return columns: last_name, first_name, email. Order results by: last_name, first_name.
10 XPSolve challenge
WHERE
Beginner
Products with Limited Stock
Find products with fewer than 200 units in stock, cheapest first. Return columns: name, category, price, stock. Order results by: price.
10 XPSolve challenge
GROUP BY
Beginner
Customers per Country
Count customers in each country, sorted by the country name. Return columns: country, customer_count. Order results by: country.
10 XPSolve challenge
Aggregations
Beginner
Total Department Budget
Calculate the combined budget of all departments. Return columns: total_budget.
10 XPSolve challenge
WHERE
Beginner
Pending Order List
List pending orders with their date and total amount. Return columns: id, order_date, total_amount. Order results by: order_date.
10 XPSolve challenge
String Functions
Beginner
Uppercase Product Catalog
Show every product name in uppercase alongside its category. Return columns: product_name, category. Order results by: id.
10 XPSolve challenge
Date Functions
Beginner
Customers Joined Since 2021
List customers who joined on or after January 1, 2021. Return columns: name, country, joined_date. Order results by: joined_date.
10 XPSolve challenge
INNER JOIN
Intermediate
Department Payroll Summary
Show each department name, employee count, and total payroll. Return columns: department_name, employee_count, total_payroll. Order results by: d.id.
25 XPSolve challenge
LEFT JOIN
Intermediate
Department Employee Coverage
Show all departments and their employee count, including departments with no employees. Return columns: department_name, employee_count. Order results by: d.id.
25 XPSolve challenge
GROUP BY
Intermediate
Order Status Summary
Show the order count and total amount for each status. Return columns: status, order_count, total_amount. Order results by: status.
25 XPSolve challenge
HAVING
Intermediate
Repeat Customers
Find customers who placed more than one order. Return columns: customer_name, order_count. Order results by: order_count DESC, customer_name.
25 XPSolve challenge
LEFT JOIN
Intermediate
Product Revenue Including Unsold
Show every product and its revenue, using zero when it has no sales. Return columns: product_name, revenue. Order results by: p.id.
25 XPSolve challenge
INNER JOIN
Intermediate
Employee and Manager Names
List each managed employee together with their manager's name. Return columns: employee, manager. Order results by: e.id.
25 XPSolve challenge
Subqueries
Intermediate
Orders Above Average Value
Find orders whose total amount is greater than the average order value. Return columns: id, customer_id, total_amount. Order results by: total_amount DESC.
25 XPSolve challenge
String Functions
Intermediate
Employee Email Usernames
Extract the portion of each employee email before the @ symbol. Return columns: email, username. Order results by: id.
25 XPSolve challenge
Date Functions
Intermediate
Monthly Completed Revenue
Calculate completed-order revenue for each month. Return columns: month, revenue. Order results by: month.
25 XPSolve challenge
Aggregations
Intermediate
Low Stock Value
Calculate inventory value for products with fewer than 200 units. Return columns: name, stock, price, inventory_value. Order results by: inventory_value DESC.
25 XPSolve challenge
Window Functions
Advanced
Dense Rank Product Prices
Use DENSE_RANK() to rank products by price inside each category while keeping equal prices at the same rank. Return columns: name, category, price, price_rank. Order results by: category, price_rank, name.
50 XPSolve challenge
Window Functions
Advanced
Customer Order Sequence
Number each customer's orders chronologically with a window function and return the customer, order date, and sequence number. Return columns: customer_id, order_id, order_date, order_number. Order results by: customer_id, order_number.
50 XPSolve challenge
CTE
Advanced
Top Three Salaries with CTE
Use a CTE to return the three highest-paid employees. Return columns: first_name, last_name, salary, salary_rank. Order results by: salary_rank.
50 XPSolve challenge
Window Functions
Advanced
PRO
Employee Share of Department Payroll
Calculate each employee's percentage share of their department payroll. Return columns: first_name, department_id, salary, payroll_share. Order results by: department_id, salary DESC.
50 XPSolve challenge
Window Functions
Advanced
PRO
Previous Order Comparison
Compare every order amount with the previous chronological order using LAG(), while preserving the complete order sequence. Return columns: id, order_date, total_amount, previous_amount. Order results by: order_date, id.
50 XPSolve challenge
HAVING
Expert
PRO
Customers Buying Both Categories
Find customers who purchased products from both Software and Infrastructure. Return columns: customer_name, category_count. Order results by: c.name.
100 XPSolve challenge
Window Functions
Expert
PRO
Days Between Customer Orders
Calculate the number of days between each customer's consecutive orders while retaining the current and previous order dates. Return columns: customer_id, order_id, order_date, previous_order_date, days_since_previous. Order results by: customer_id, order_date.
100 XPSolve challenge
WHERE
Beginner
Employees Earning Above 60000
List employee names and salaries above 60000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
Employees Earning Above 65000
List employee names and salaries above 65000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 70000
List employee names and salaries above 70000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 75000
List employee names and salaries above 75000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 80000
List employee names and salaries above 80000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 85000
List employee names and salaries above 85000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 90000
List employee names and salaries above 90000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
PRO
Employees Earning Above 100000
List employee names and salaries above 100000, ordered by salary descending. Return columns: first_name, last_name, salary. Order results by: salary DESC, id.
10 XPSolve challenge
WHERE
Beginner
Employees Earning Below 60000
Return employee names and salaries below 60000, lowest salary first. Return columns: first_name, last_name, salary. Order results by: salary, id.
10 XPSolve challenge
WHERE
Beginner
Employees Earning Below 65000
Return employee names and salaries below 65000, lowest salary first. Return columns: first_name, last_name, salary. Order results by: salary, id.
10 XPSolve challenge
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Structured SQL practice
How to use the SQL challenge library
Start with a topic you can explain in plain language, inspect the schema, write the smallest correct query, and validate the result. Move from SELECT and filtering to JOINs, grouped reports, CTEs and window functions as your accuracy improves.