INNER JOIN

INNER JOIN statement is used to retrieve matched data by specified column(s) between two tables. This statement returns data when at least one match is available between joined columns.

This simple example will depict us logic of inner join

CREATE TABLE TABLE_1
(
ID1 INT,
NUMBER1 VARCHAR(20)
)

INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(1,'One')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(2,'Two')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(3,'Three')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(4,'Four')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(5,'Five')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(6,'Six')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(7,'Seven')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(8,'Eight')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(9,'Nine')
INSERT INTO TABLE_1(ID1, NUMBER1) VALUES(10,'Ten')

select * from TABLE_1

ID1	NUMBER1
1	One
2	Two
3	Three
4	Four
5	Five
6	Six
7	Seven
8	Eight
9	Nine
10	Ten

CREATE TABLE TABLE_2
(
ID2 INT,
NUMBER2 VARCHAR(20)
)

INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(6,'Six')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(7,'Seven')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(8,'Eight')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(9,'Nine')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(10,'Ten')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(11,'Eleven')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(12,'Twelve')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(13,'Thirteen')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(14,'Fourteen')
INSERT INTO TABLE_2(ID2, NUMBER2) VALUES(15,'Fifteen')

select * from TABLE_2

ID2	NUMBER2
6	Six
7	Seven
8	Eight
9	Nine
10	Ten
11	Eleven
12	Twelve
13	Thirteen
14	Fourteen
15	Fifteen

select * from TABLE_1 inner join TABLE_2 on TABLE_1 .ID = TABLE_2 .ID 

ID1	NUMBER1	ID2	NUMBER2
6	Six	6	Six
7	Seven	7	Seven
8	Eight	8	Eight
9	Nine	9	Nine
10	Ten	10	Ten

Note

NULL Values will not match in JOINS