--sample dataCREATE TABLE employees ( id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(100), department_id INT, salary DECIMAL(10, 2), hire_date DATE); alter table employees add index idx1(department_id);alter table employees add index idx2(salary);alter table employees add index idx3(hire_date);-- 예제 데이터 삽입INSERT INTO employees (name, department_id, salary, hire_date)VALUES ..
