SQL LEFT JOIN

The LEFT JOIN returns all rows from the left table (table1), and only the matched rows from the right table (table2).

If there is no match in the right table, the result for the columns from the right table will be NULL.

The LEFT JOIN and LEFT OUTER JOIN keywords are equal - the OUTER keyword is optional.

LEFT JOIN Syntax

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

Note

The syntax combines two tables based on a related column , and the ON keyword is used to specify the matching condition.

Below is a selection from the "Customers" table:

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 ConstituciÃ³n 2222	MÃ©xico D.F.	05021	Mexico
3	Antonio Moreno TaquerÃa	Antonio Moreno	Mataderos 2312	MÃ©xico D.F.	05023	Mexico

And a selection from the "Orders" table:

OrderID	CustomerID	EmployeeID	OrderDate	ShipperID
10308	2	7	1996-09-18	3
10309	37	3	1996-09-19	1
10310	77	8	1996-09-20	2

Here we see that the related column between the two tables above, is the "CustomerID" column.