All rows from the left table.
✍️ 3 exercises + code challenge in this lessonLEFT JOIN returns every row from the left table, and the matching rows from the right table. When there is no match, the right side is NULL.
This is perfect for questions like "which customers have never ordered?": left join, then keep rows where the right side is NULL.
Mastering SQL LEFT JOIN 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.
SELECT c.CustomerName, o.OrderID
FROM Customers c
LEFT JOIN Orders o ON o.CustomerID = c.CustomerID
ORDER BY c.CustomerName;
-- Customers with no orders at all
SELECT c.CustomerName
FROM Customers c
LEFT JOIN Orders o ON o.CustomerID = c.CustomerID
WHERE o.OrderID IS NULL;Check what you learned in “SQL LEFT JOIN”.
Keep all customers, even without orders.
SELECT * FROM Customers c Orders o ON o.CustomerID = c.CustomerID;
In a LEFT JOIN, what do the right-side columns contain when there is no match?
Select the CustomerName of customers who have never placed an order, sorted by name.
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