MySQL Joins, MySQL INNER, LEFT, RIGHT Joins For Beginners

MySQL Tutorial Point – We would love to share with you how to use MySQL JOINS with example. Basically MySQL Provide following types of Join INNER JOIN, LEFT JOIN, RIGHT JOIN & SELF JOIN.

In this blog post we will discuss about What is MySQL join? Type of Joins etc

Here are the different types of the JOINs in SQL:

• INNER JOIN: Returns records that have matching values in both tables
• LEFT JOIN: Returns all records from the left table, and the matched records from the right table
• RIGHT JOIN: Returns all records from the right table, and the matched records from the left table
• FULL JOIN: Returns all records when there is a match in either left or right table
• CROSS JOIN: This join produces a result where the number of rows in the first table gets multiplied with the rows in the second table.
• SELF JOIN: Self-join is a regular join and here the table joins with itself only.

MySQL Joins

JOINS can be used in MySQL with the Select Statement. It is used to get data from two or more database tables. When we want to get the records from two or more database tables, then we need to use MySQL JOINS at that time. The tables are mutually related using primary and foreign keys.

INNER JOIN MySQL

In MySQL INNER JOIN clause selects records if the given column values matching in both tables. MySQL INNER JOIN is used to fetch data from multiple tables.

Syntax

 SELECT table1.column, table2.column 
 FROM table1   
 INNER JOIN table2  
 ON table1.column = table2.column;  

INNER JOIN MySQL Example

If we want to select data from two country and city, then we can run the following query (Inner Join) :-

 SELECT city, country
 FROM city
 INNER JOIN country ON
 city.country_id = country.country_id;

LEFT JOIN MySQL

The MySQL LEFT JOIN clause returns all rows from the left table, even if there are no matches in the right table, The result is NULL from the right side.

Syntax

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

LEFT JOIN MySQL Example

Let’s return a list of all users table. And if the users shares the same last name with an actor table :-

SELECT 
     u.user_id, 
     u.first_name, 
     u.last_name,
     a.autor_id,
     a.first_name,
     a.last_name
 FROM users u
 LEFT JOIN actor a 
 ON u.last_name = a.last_name
 ORDER BY u.last_name;

Right JOIN MySQL

The MySQL Right JOIN clause returns all rows from the right table, even if there are no matches in the right table, The result is NULL from the right side.

Syntax

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

Right JOIN MySQL Example

Let’s return a list of all users table. And if the users shares the same last name with an actor table :-

SELECT 
     u.user_id, 
     u.first_name, 
     u.last_name,
     a.autor_id,
     a.first_name,
     a.last_name
 FROM users u
 RIGHT JOIN actor a 
 ON u.last_name = a.last_name
 ORDER BY a.last_name;

Self Join MySQL

The MySQL self join is used to join a table to itself when using a join clause.

MySQL self join is useful when you want to combine the records in a table with other records in the same table.

Self Join MySQL Example

SELECT 
     a.customer_id, 
     a.first_name, 
     a.last_name, 
     b.customer_id,
     b.first_name, 
     b.last_name 
 FROM customer a
 INNER JOIN customer b
 ON a.last_name = b.first_name;

Cross Join MySQL

This join produces a result where the number of rows in the first table gets multiplied with the rows in the second table. This kind of result is called the Cartesian Product. If we use the WHERE clause with this join, then this will work as an inner join.

Cross Join MySQL Example

SELECT c.first_name, c.last_name, company.name
FROM customer c
CROSS JOIN company;

Note

MySQL Self join can also use with left join and right join

Conclusion

In this MySQL tutorial point – we have described about mysql joins with example.