A subquery is a query nested inside another query. It can appear in:
WHERE:WHERE Price > (SELECT AVG(Price) FROM Products)FROM: as a temporary table (a "derived table").SELECT: to calculate a value per row (a "correlated subquery").
SQL Subqueries
Queries inside queries.
✍️ 3 exercises + code challenge in this lessonKey Takeaways: SQL Subqueries
Mastering SQL Subqueries helps you write clean and reliable SQL code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
SQL Subqueries Code Example
SQL-- Products priced above average
SELECT ProductName, Price FROM Products
WHERE Price > (SELECT AVG(Price) FROM Products);
-- Number of orders per customer, as a column
SELECT CustomerName,
(SELECT COUNT(*) FROM Orders o WHERE o.CustomerID = c.CustomerID) AS OrderCount
FROM Customers c
ORDER BY OrderCount DESC;
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SQL Subqueries Practice Exercises
Check what you learned in “SQL Subqueries”.
/ 3 solved
Fill in the blank
Compare with the average price.
WHERE Price > ( AVG(Price) FROM Products)
✓ Correct!
Not quite. Try again.
Multiple choice
Where can a subquery appear?
✓ Correct!
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Code challenge
Select the ProductName of the most expensive product using a subquery with MAX.
Write the code in the live editor. Your answer is checked automatically.
✓ Solved
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