The best SQL connection (JOIN) Tutorial In 2024, In this tutorial you can learn SQL JOIN,The demo database,Examples,Different SQL JOIN,
SQL join for the line from two or more tables together.
SQL JOIN clause to the rows from two or more tables together, based on common fields between the tables.
The most common type of JOIN: SQL INNER JOIN (simple JOIN). SQL INNER JOIN JOIN returns all rows that satisfy the conditions from multiple tables.
In this tutorial, we will use w3big sample database.
The following is a selected "Websites" table data:
+----+--------------+---------------------------+-------+---------+ | id | name | url | alexa | country | +----+--------------+---------------------------+-------+---------+ | 1 | Google | https://www.google.cm/ | 1 | USA | | 2 | 淘宝 | https://www.taobao.com/ | 13 | CN | | 3 | 本教程 | http://www.w3write.com/ | 4689 | CN | | 4 | 微博 | http://weibo.com/ | 20 | CN | | 5 | Facebook | https://www.facebook.com/ | 3 | USA | | 7 | stackoverflow | http://stackoverflow.com/ | 0 | IND | +----+---------------+---------------------------+-------+---------+
Here is the data "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 | 2016-05-16 | | 9 | 3 | 201 | 2016-05-17 | +-----+---------+-------+------------+ 9 rows in set (0.00 sec)
Please note, "Websites" table "id" column point "access_log" field in the table "site_id". The above two tables by "site_id" column linking.
Then, if we run the following SQL statement (including INNER JOIN):
Execute the above SQL output results are as follows:
Before we continue to explain instance, let's list the different SQL JOIN types you can use: