SQL LEFT JOIN Keyword - W3Schools

Trang chủ » Câu Lệnh Join 2 Bảng Trong Sql » SQL LEFT JOIN Keyword - W3Schools

Có thể bạn quan tâm

SQL LEFT JOIN Keyword ❮ Previous Next ❯

SQL LEFT JOIN Keyword

The LEFT JOIN keyword returns all records from the left table (table1), and the matching records from the right table (table2). The result is 0 records from 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;

Note: In some databases LEFT JOIN is called LEFT OUTER JOIN.

SQL LEFT JOIN

Demo Database

In this tutorial we will use the well-known Northwind sample database.

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 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

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

Example

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

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

❮ Previous Next ❯ ★ +1 Sign in to track progress

Từ khóa » Câu Lệnh Join 2 Bảng Trong Sql