MySQL UNION Operator
The UNION operator in MySQL is used to combine the result sets of two or more SELECT statements into a single result set.
Example:
SELECT employee_id, employee_name
FROM employees
WHERE department_id = 1
UNION
SELECT employee_id, employee_name
FROM employees
WHERE department_id = 2;This query retrieves the employee IDs and names from the employees table for employees in department 1 and department 2, combining the results into a single result set.
The UNION operator removes duplicate rows by default. If you want to include duplicate rows, you can use the UNION ALL operator.