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SQL LEFT JOIN

SQL LEFT JOIN Keyword

The LEFT JOIN keyword retrieves all records from the left table (table1) and any matching records from the right table (table2). If there’s no match, the result will show NULL for records from the right side.

LEFT JOIN Syntax

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

Note: In certain databases, LEFT JOIN is referred to as LEFT OUTER JOIN.

Image

Demo Database

In this tutorial, we’ll utilize the popular Northwind sample database.

Here’s a segment 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 Constitución 2222

México D.F.

05021

Mexico

3

Antonio Moreno Taquería

Antonio Moreno

Mataderos 2312

México 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

SQL LEFT JOIN Example

This SQL statement retrieves all customers along with any associated orders they may have.

Example

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

Keep in mind: The LEFT JOIN keyword retrieves all records from the left table (Customers), irrespective of whether there are corresponding matches in the right table (Orders).