SQL (Structured Query Language) is a programming language used to manage and manipulate relational databases. It is used to create, modify, and retrieve data from databases. SQL Right Join is one of the types of SQL Joins used to combine data from two or more tables based on a common column between them.
A Right Join returns all the rows from the right table and matching rows from the left table. If there are no matching rows in the left table, the result will contain NULL values.
The syntax for SQL Right Join is as follows:
SELECT column_name(s) FROM table1 RIGHT JOIN table2 ON table1.column_name = table2.column_name;
Let's take an example to understand SQL Right Join better:
We have two tables, "employees" and "departments". The "employees" table contains information about the employees such as their name, age, and department ID. The "departments" table contains information about the departments such as their name and ID.
Employees Table:
| Name | Age | Department ID |
|---|---|---|
| John | 25 | 1 |
| Jane | 30 | 2 |
| Bob | 35 | 3 |
Departments Table:
| ID | Name |
|---|---|
| 1 | Marketing |
| 2 | Finance |
| 4 | IT |
Now, let's say we want to retrieve all the employees and their department names. We can use SQL Right Join to achieve this:
SELECT employees.name, departments.name FROM employees RIGHT JOIN departments ON employees.department_id = departments.id;
The result of this query will be:
| Name | Name |
|---|---|
| John | Marketing |
| Jane | Finance |
| NULL | IT |
As we can see, the result contains all the rows from the "departments" table and matching rows from the "employees" table. Since there is no matching row for the department with ID 4 in the "employees" table, the result contains NULL values for the "name" column.
SQL Right Join is useful when we want to retrieve all the rows from the right table and matching rows from the left table. It is commonly used in situations where we want to retrieve data from two or more tables based on a common column between them.
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