LEFT JOIN

SQL LEFT JOIN Kalit So'zi

SQL LEFT JOIN Kalit So'zi

LEFT JOIN kalit so'zi chap jadvaldan (table1) barcha yozuvlarni, va o'ng jadvaldan (table2) mos yozuvlarni qaytaradi. Agar moslik bo'lmasa, o'ng tarafdan 0 yozuv qaytariladi.

LEFT JOIN Sintaksisi

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

Eslatma

Ba'zi bazalarda LEFT JOIN LEFT OUTER JOIN deb ham ataladi.

SQL LEFT JOIN

Demo Ma'lumotlar Bazasi

Ushbu o'quv qo'llanmada biz mashhur Northwind namunaviy ma'lumotlar bazasidan foydalanamiz.

Quyida "Customers" jadvalidan bir tanlov:

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

Va "Orders" jadvalidan bir tanlov:

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 Misoli

Quyidagi SQL bayonoti barcha mijozlarni va ularning buyurtmalarini tanlaydi:

Misol

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