SQL LEFT JOIN

The LEFT JOIN keyword returns all rows from the left table (table_name1), even if there are no matches in the right table (table_name2).

SQL LEFT JOIN Syntax

SELECT column_name(s) FROM table_name1 LEFT JOIN table_name2 ON table_name1.column_name=table_name2.column_name

In some databases LEFT JOIN is called LEFT OUTER JOIN.

SQL LEFT JOIN Example

The "Persons" table:

Id	LastName	FirstName	Address	City
1	Navis	Anto	Madras	TVL
2	Ji	Bala	Bombay	TVL
3	Christopher	Franklin	America	KK

The "Orders" table:

Id	OrderNo	Id
1	77895	3
2	44678	3
3	22456	1
4	24562	1
5	34764	15

Now we want to list all the persons and their orders - if any, from the tables above.

We use the following SELECT statement:

SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo FROM Persons LEFT JOIN Orders ON Persons.Id=Orders.Id ORDER BY Persons.LastName

The result-set will look like this:

LastName	FirstName	OrderNo
Navis	Anto	22456
Navis	Anto	24562
Christopher	Franklin	77895
Christopher	Franklin	44678
Ji	Bala

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