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LEFT JOIN

The SQL LEFT JOIN combines rows from two or more tables based on a related column between them and returns all rows from the left table (table1) and the matched rows from the right table (table2). If there is no match, the result is NULL on the right side.

Syntax​

SELECT column_name(s)
FROM table1
LEFT JOIN table2
ON table1.column_name = table2.column_name;

How SQL LEFT JOIN Works​

The LEFT JOIN keyword returns all records from the left table (table1), and the matched records from the right table (table2). The result is NULL from the right side, if there is no match.

LEFT JOIN Diagram

SQL LEFT JOIN Example​

Let's assume we have two tables: Orders and Customers.

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
LEFT JOIN Customers
ON Orders.CustomerID = Customers.CustomerID;

This SQL statement would return all OrderID and the matching CustomerName. If there is no match, the result is NULL.