SQL - Right Join

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Joins are used to retrieve records from multiple tables based on a given condition. A Join includes the records that satisfy the given condition and outer join results a table that contains both matched and unmatched rows.

Left Outer Join, as discussed in the previous chapter, is used to find the union of two tables with respect to the left table. In this chapter, let us discuss more about the Right outer join.

Right Join in SQL

The Right Join or Right Outer Join query in SQL returns all rows from the right table, even if there are no matches in the left table. This means that if the ON clause matches 0 (zero) records in the left table; the join will still return a row in the result, but with a NULL value in each column of the left table.

In short, a right join returns all the values from the right table, plus matched values from the left table or NULL in case of no matching join predicate.

Note that the resultant table displayed after implementing the Right Join is not stored anywhere in the database.

Syntax

Following is the basic syntax of Right Join in SQL −

SELECT table1.column1, table2.column2...
FROM table1
RIGHT JOIN table2
ON table1.common_field = table2.common_field;

Example

The tables we are using in this example are named “Customers” and “Orders”.

Assume we are creating a table named Customers, which contains the personal details of customers including their name, age, address and salary etc.

CREATE TABLE CUSTOMERS (
   ID INT NOT NULL,
   NAME VARCHAR (20) NOT NULL,
   AGE INT NOT NULL,
   ADDRESS CHAR (25),
   SALARY DECIMAL (18, 2),       
   PRIMARY KEY (ID)
);

Now insert values into this table using the INSERT statement as follows −

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (1, 'Ramesh', 32, 'Ahmedabad', 2000.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (2, 'Khilan', 25, 'Delhi', 1500.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (3, 'kaushik', 23, 'Kota', 2000.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (4, 'Chaitali', 25, 'Mumbai', 6500.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (5, 'Hardik', 27, 'Bhopal', 8500.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (6, 'Komal', 22, 'MP', 4500.00 );

INSERT INTO CUSTOMERS (ID,NAME,AGE,ADDRESS,SALARY)
VALUES (7, 'Muffy', 24, 'Indore', 10000.00 );

The table will be created as −

+----+----------+-----+-----------+----------+
| ID | NAME     | AGE | ADDRESS   | SALARY   |
+----+----------+-----+-----------+----------+
|  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |
|  2 | Khilan   |  25 | Delhi     |  1500.00 |
|  3 | Kaushik  |  23 | Kota      |  2000.00 |
|  4 | Chaitali |  25 | Mumbai    |  6500.00 |
|  5 | Hardik   |  27 | Bhopal    |  8500.00 |
|  6 | Komal    |  22 | MP        |  4500.00 |
|  7 | Muffy    |  24 | Indore    | 10000.00 |
+----+----------+-----+-----------+----------+

Let us create another table Orders, containing the details of orders made and the date they are made on.

CREATE TABLE ORDERS (
   OID INT NOT NULL,
   DATE VARCHAR (20) NOT NULL,
   CUSTOMER_ID INT NOT NULL,
   AMOUNT DECIMAL (18, 2),
);

Using the INSERT statement, insert values into this table as follows −

INSERT INTO ORDERS (OID, DATE, CUSTOMER_ID, AMOUNT)
VALUES (102, '2009-10-08 00:00:00', 3, 3000.00);

INSERT INTO ORDERS (OID, DATE, CUSTOMER_ID, AMOUNT)
VALUES (100, '2009-10-08 00:00:00', 3, 1500.00);

INSERT INTO ORDERS (OID, DATE, CUSTOMER_ID, AMOUNT)
VALUES (101, '2009-11-20 00:00:00', 2, 1560.00);

INSERT INTO ORDERS (OID, DATE, CUSTOMER_ID, AMOUNT)
VALUES (103, '2008-05-20 00:00:00', 4, 2060.00);

The table is displayed as follows −

+-----+---------------------+-------------+---------+
| OID | DATE                | CUSTOMER_ID | AMOUNT  |
+-----+---------------------+-------------+---------+
| 102 | 2009-10-08 00:00:00 |           3 | 3000.00 |
| 100 | 2009-10-08 00:00:00 |           3 | 1500.00 |
| 101 | 2009-11-20 00:00:00 |           2 | 1560.00 |
| 103 | 2008-05-20 00:00:00 |           4 | 2060.00 |
+-----+---------------------+-------------+---------+

Right join Query

Now, let us join these two tables using the Right Join query as follows.

SELECT ID, NAME, AMOUNT, DATE
FROM CUSTOMERS
RIGHT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID;

Output

This would produce the following result −

+------+----------+---------+---------------------+
| ID   | NAME     | AMOUNT  | DATE                |
+------+----------+---------+---------------------+
|    3 | Kaushik  | 3000.00 | 2009-10-08 00:00:00 |
|    3 | Kaushik  | 1500.00 | 2009-10-08 00:00:00 |
|    2 | Khilan   | 1560.00 | 2009-11-20 00:00:00 |
|    4 | Chaitali | 2060.00 | 2008-05-20 00:00:00 |
+------+----------+---------+---------------------+

Joining Multiple Tables with Right Join

Like Left Join, Right Join also joins multiple tables. However, the contrast occurs where the second table is returned as a whole instead of the first.

In addition, the rows of first table are matched with the rows in second table. If the records are not matched and the number of records in the second table is greater than the first, NULL is returned as the values in first table.

Syntax

Following is the syntax to join multiple tables using Right Join −

SELECT column1, column2, column3…
FROM table1
RIGHT JOIN table2
ON table1.column_name = table2.column_name
LEFT JOIN table3
ON table2.column_name = table3.column_name
.
.
.

Example

Here, let us consider the previously created tables “Customers” and “Orders”; along with the newly created table “Employee”.

We will try to create the Employee table using the query below −

CREATE TABLE EMPLOYEE (
   EID INT NOT NULL,
   EMPLOYEE_NAME VARCHAR (30) NOT NULL,
   SALES_MADE DECIMAL (20)
);

Now, we can insert values into this empty tables using the INSERT statement as follows −

INSERT INTO EMPLOYEE VALUES (102, 'SARIKA', 4500);
INSERT INTO EMPLOYEE VALUES (100, 'ALEKHYA', 3623);
INSERT INTO EMPLOYEE VALUES (101, 'REVATHI', 1291);
INSERT INTO EMPLOYEE VALUES (103, 'VIVEK', 3426);
INSERT INTO EMPLOYEE VALUES (100, 'ALEKHYA', 3456);

The details of Employee table can be seen below.

+-----+---------------+------------+
| EID | EMPLOYEE_NAME | SALES_MADE |
+-----+---------------+------------+
| 102 | SARIKA        |       4500 |
| 100 | ALEKHYA       |       3623 |
| 101 | REVATHI       |       1291 |
| 103 | VIVEK         |       3426 |
| 100 | ALEKHYA       |       3456 |
+-----+---------------+------------+

Let us try to join these three tables using the Right Join query given below −

SELECT CUSTOMERS.ID, CUSTOMERS.NAME, ORDERS.DATE, EMPLOYEE.EMPLOYEE_NAME
FROM CUSTOMERS
RIGHT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
RIGHT JOIN EMPLOYEE
ON ORDERS.OID = EMPLOYEE.EID;

Through this query, we are trying to display the records of Customer IDs, Customer names, Orders made on specific dates and names of the employees that sold them.

Output

The resultant table is obtained as follows −

+------+----------+---------------------+---------------+
| ID   | NAME     | DATE                | EMPLOYEE_NAME |
+------+----------+---------------------+---------------+
|    3 | Kaushik  | 2009-10-08 00:00:00 | SARIKA        |
|    3 | Kaushik  | 2009-10-08 00:00:00 | ALEKHYA       |
|    2 | Khilan   | 2009-11-20 00:00:00 | REVATHI       |
|    4 | Chaitali | 2008-05-20 00:00:00 | VIVEK         |
|    3 | Kaushik  | 2009-10-08 00:00:00 | ALEKHYA       |
+------+----------+---------------------+---------------+

Right Join with WHERE Clause

A WHERE Clause is used to filter out records that satisfy the condition specified by it. This clause can be used with the Right Join technique to apply certain constraint on the records fetched as a result.

Syntax

The syntax of Right Join when used with WHERE clause is given below −

SELECT column_name(s)
FROM table_name1
RIGHT JOIN table_name2
ON table_name1.column_name = table_name2.column_name
WHERE condition

Example

Records in the combined database tables can be filtered using the WHERE clause. Consider the previous two tables Customers and Orders; and try to join them using the right join query by applying some constraints using the WHERE clause.

SELECT ID, NAME, DATE, AMOUNT FROM CUSTOMERS
RIGHT JOIN ORDERS
ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
WHERE ORDERS.AMOUNT > 1000.00;

Output

The resultant table after applying the where clause with right join contains the rows that has amount values greater than 1000.00 −

+------+----------+---------------------+---------+
| ID   | NAME     | DATE                | AMOUNT  |
+------+----------+---------------------+---------+
|    3 | Kaushik  | 2009-10-08 00:00:00 | 3000.00 |
|    3 | Kaushik  | 2009-10-08 00:00:00 | 1500.00 |
|    2 | Khilan   | 2009-11-20 00:00:00 | 1560.00 |
|    4 | Chaitali | 2008-05-20 00:00:00 | 2060.00 |
+------+----------+---------------------+---------+