MariaDB FULL JOIN

MariaDB does not support FULL JOIN keyword. But, a FULL JOIN on two tables can be achieved by using three keywords: LEFT JOIN, RIGHT JOIN and UNION keywords.

Example:

Consider a database containing tables called Employee and Contact_Info with the following records:

Table 1: Employee table

Table 2: Contact_Info table

• To implement full join in MariaDB with Employee and Contact_Info tables based on matching column EmpID, the query is given below. This will fetch Name and Age columns from Employee table and Address column from Contact_Info table.

  SELECT Employee.Name, Employee.Age, Contact_Info.Address 
  FROM Employee
  LEFT JOIN Contact_Info
  ON Employee.EmpID = Contact_Info.EmpID
  
  UNION
  
  SELECT Employee.Name, Employee.Age, Contact_Info.Address 
  FROM Employee
  RIGHT JOIN Contact_Info
  ON Employee.EmpID = Contact_Info.EmpID;
  

  
  

  This will produce the result as shown below:

  Name	Age	Address
  John	25
  Marry	24	Brooklyn, New York, USA
  Jo	27	Grenelle, Paris, France
  Kim	30	Geuzenveld, Amsterdam, Netherlands
  Ramesh	28
  Huang	28	Yizhuangzhen, Beijing, China
  		Yishun, Singapore
  		Koto City, Tokyo, Japan

• To fetch all fields of a table, table.* keyword is used, for example - to fetch all fields of the Employee table, Employee.* is used in the query given below:

  SELECT Employee.*, Contact_Info.Address 
  FROM Employee
  LEFT JOIN Contact_Info
  ON Employee.EmpID = Contact_Info.EmpID
  
  UNION
  
  SELECT Employee.*, Contact_Info.Address 
  FROM Employee
  RIGHT JOIN Contact_Info
  ON Employee.EmpID = Contact_Info.EmpID;
  

  
  

  This result of the following code will be:

  EmpID	Name	City	Age	Salary	Address
  1	John	London	25	3000
  2	Marry	New York	24	2750	Brooklyn, New York, USA
  3	Jo	Paris	27	2800	Grenelle, Paris, France
  4	Kim	Amsterdam	30	3100	Geuzenveld, Amsterdam, Netherlands
  5	Ramesh	New Delhi	28	3000
  6	Huang	China	28	2800	Yizhuangzhen, Beijing, China
  					Yishun, Singapore
  					Koto City, Tokyo, Japan