Equi-Join

Equi-Join:

Consider two tables: employees and departments. Both tables have a common column named department_id.

Table: employees

employee_id	employee_name	department_id	salary
1	Alice	101	5000
2	Bob	102	6000
3	Charlie	101	5500
4	David	103	7000

Table: departments

department_id	department_name
101	HR
102	IT
103	Finance

SQL Equi-Join Query

SELECT employees.employee_id, employees.employee_name, employees.salary, departments.department_name FROM employees JOIN departments ON employees.department_id = departments.department_id;

 Result:

employee_id	employee_name	salary	department_name
1	Alice	5000	HR
2	Bob	6000	IT
3	Charlie	5500	HR
4	David	7000	Finance

 In this example, the JOIN keyword is used to combine rows from the employees table with the matching rows from the departments table based on the common column department_id. The result includes columns from both tables where the join condition is satisfied. This type of join is known as an equi-join because it uses equality comparison in the join condition.