SQL INNER JOIN Keyword

SQL INNER JOIN Keyword

The INNER JOIN keyword returns rows when at least one match exists in the table.

INNER JOIN Keyword Syntax

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

Note:INNER JOIN is the same as JOIN.

Original Table (used in examples):

"Persons" Table:

Id_P LastName FirstName Address City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York
3 Carter Thomas Changan Street Beijing

"Orders" Table:

Id_O OrderNo Id_P
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34764 65

Inner Join (INNER JOIN) Example

Now, we want to list everyone's orders.

You can use the following SELECT statement:

SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM Persons
INNER JOIN Orders
ON Persons.Id_P=Orders.Id_P
ORDER BY Persons.LastName

Result Set:

LastName FirstName OrderNo
Adams John 22456
Adams John 24562
Carter Thomas 77895
Carter Thomas 44678

The INNER JOIN keyword returns rows when there is at least one match in the table. If there is no match in the 'Orders' table for the rows in 'Persons', these rows will not be listed.