SQL INNER JOIN Keyword

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

SQL INNER JOIN syntax

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

Or:

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

Note: INNER JOIN is the same as JOIN.

SQL INNER JOIN

Demo Database

In this tutorial we will use the php sample database.

The following is the data selected from the "Websites" table:

+----+--------------+--- ------------------------+------+---------+
| id | name | url                                                                    --------+-------+---------+
| 1 | Google | https://www.google.cm/ | 1 | USA |
| 2 | Taobao | https://www.taobao.com/ | 13 | CN |
| 3 | php Chinese website | //m.sbmmt.com/ | 4689 | CN |
| 4 | Weibo | http://weibo.com/ | 20 | CN |
| 5 | Facebook | https://www.facebook.com/ | 3 | USA |
| 7 | stackoverflow | http://stackoverflow.com/ | 0 | IND |
+----+---------------+----------- ----------------+------+---------+

The following is the data of the "access_log" website access record table:

mysql> SELECT * FROM access_log;
+-----+--------- +-------+------------+
| aid | site_id | count | date |
+-----+------ ---+-------+------------+
| 1 | 1 | 45 | 2016-05-10 |
| 2 | 3 | 100 | 2016-05-13 |
| 3 | 1 | 230 | 2016-05-14 |
| 4 | 2 | 10 | 2016-05-14 |
| 5 | 5 | 205 | 2016 -05-14 |
| 6 | 4 | 13 | 2016-05-15 |
| 7 | 3 | 220 | 2016-05-15 |
| 8 | 5 | 545 | 201 6-05 -16 |
| 9 | 3 | 201 | 2016-05-17 |
+-----+----------+------+--- ---------+
9 rows in set (0.00 sec)

SQL INNER JOIN Example

The following SQL statement will return all Website access record:

Example

            SELECT Websites.name, access_log.count, access_log.date
FROM Websites
INNER JOIN access_log
ON Websites.id=access_log.site_id
ORDER BY access_log.count;

The output result of executing the above SQL is as follows:

Note: INNER JOIN keyword is in the table Return rows if there is at least one match. Rows in the "Websites" table are not listed if they do not have a match in the "access_log".