SQL LEFT JOIN

SQL LEFT JOIN Description

The keyword LEFT JOIN returns all records from the left table (table1) and the corresponding records from the right table (table2).

The result will be 0 entries on the right side if there is no match.

LEFT JOIN Syntax

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

In some databases, LEFT JOIN is called LEFT OUTER JOIN.

SQL INNER JOIN

Demonstration database

In this tutorial we will use the famous example database "Northwind".

Below is a sample from the table "Customers" ("Customers"):

CustomerID	CustomerName	ContactName	Address	City	PostalCode	Country
1	Alfreds Futterkiste	Maria Anders	Obere Str. 57	Berlin	12209	Germany
2	Ana Trujillo Emparedados y helados	Ana Trujillo	Avda. de la Constitución 2222	México D.F.	5021	Mexico
3	Antonio Moreno Taquería	Antonio Moreno	Mataderos 2312	México D.F.	5023	Mexico
4	Around the Horn	Thomas Hardy	120 Hanover Sq.	London	WA1 1DP	UK
5	Berglunds snabbköp	Christina Berglund	Berguvsvägen 8	Luleå	S-958 22	Sweden

And the sample from the table "Orders" ("Orders"):

ProductID	OrderID	CustomerID	EmployeeID	OrderDate	ShipperID
1	10248	90	5	1996-07-04	3
2	10249	81	6	1996-07-05	1
3	10250	34	4	1996-07-08	2
4	10251	84	3	1996-07-08	1
5	10252	76	4	1996-07-09	2

SQL LEFT JOIN Example

The following SQL statement will select all customers and any orders they may have:

Run SQLSELECT Customers.CustomerName, Orders.OrderID 
FROM Customers 
LEFT JOIN Orders ON Customers.CustomerID = Orders.CustomerID 
ORDER BY Customers.CustomerName

The LEFT JOIN keyword returns all records from the left table (Customers), even if there are no matches in the right table (Orders).