SQL INNER JOIN Keyword

SQL INNER JOIN Keyword :

The INNER JOIN keyword return rows when there is at least one match in both tables.

SQL INNER JOIN Syntax :

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

PS: INNER JOIN is the same as JOIN.
---------------------------------

SQL INNER JOIN Example :

The "Persons" table:

P_Id LastName FirstName Address City
-----------------------------------
1 Hansen Ola Timoteivn 10 Sandnes
2 Svendson Tove Borgvn 23 Sandnes
3 Pettersen Kari Storgt 20 Stavanger

The "Orders" table:

O_Id OrderNo P_Id
-----------------
1 77895 3
2 44678 3
3 22456 1
4 24562 1
5 34764 15

Now we want to list all the persons with any orders.

We use the following SELECT statement:

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

The result-set will look like this:

LastName FirstName OrderNo
--------------------------
Hansen Ola 22456
Hansen Ola 24562
Pettersen Kari 77895
Pettersen Kari 44678