LEFT JOIN shows every row from the left table, and pulls in a match from the right table wherever one exists. Where there's no match, you get NULL. It's extremely useful for reports that need to include customers who don't have any orders yet.
sql
SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;You should see
+--------------------+---------+ | CustomerName | OrderID | +--------------------+---------+ | Alfreds Futterkiste| NULL | | Ana Trujillo | 10308 | | Antonio Moreno | 10309 | | Around the Horn | NULL | +--------------------+---------+ What learners should notice: Customers without any orders still show up here. That's the key difference from INNER JOIN. Practical use: If you want to pull a list of "no orders yet" customers, pair LEFT JOIN with WHERE Orders.OrderID IS NULL.