INNER JOIN

Today let's discuss on the advance and the most important part that is how to join the two tables. Their are many ways to join a table but it is up to you what type of joining do you need The two type of joining is the INNER JOIN and OUTER JOIN.

Lets start with INNER JOIN.
By the term inner join we mean joining two or more table under some condition i.e through WHERE clause. It is just like a JOIN statement. Lets see the example

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

TABLE A

P_Id	LastName	FirstName	Address	City
1	ABC	DEF	Street 10	PPP
2	GHI	IJK	Street 20	QQQ
3	LMN	OPQ	Street 30	DDD

TABLE B

O_Id	OrderNo	P_Id
1	111111	1
2	222222	2
3	444444	3
4	555555	4
5	666666	5

Now we ask for INNER JOIN
SELECT Persons.LastName, Persons.FirstName, Orders.OrderNo
FROM TABLE A
INNER JOIN TABLE B
ON TABLE A.P_Id=TABLE B.P_Id
ORDER BY TABLE A.LastName

The out put that it will return will be

LastName	FirstName	OrderNo
ABC	DEF	111111
GHI	IJK	222222
LMN	OPQ	333333

The INNER JOIN keyword will return the number of rows that are common in both the table , like here the column that are returned are of two common people Hansen, Pettersen.