SELECT last_name salary(1+NULL(commission_pct,0)) salary
WHERE(salary*(1+IFNULL(commission_pct,0)) NOT BETWEEN 5000 AND 12000);
SELECT last_name name,department_id FROM employees WHERE department_id IN (20,50);
SELECT last_name name,job_id FROM employees WHERE manager_id IS NULL;
SELECT last_name name,salary*(1+IFNULL(commission_pct,0)) "工资",commission_pct "奖金级别" FROM employees
WHERE commission_pct IS NOT null;
SELECT last_name name FROM employees WHERE last_name LIKE '__a%';
SELECT last_name name FROM employees WHERE last_name LIKE '%a%'AND last_name LIKE '%k%';
SELECT first_name name FROM employees WHERE first_name LIKE '%e';
SELECT last_name name,job_id "工种" FROM employees WHERE department_id BETWEEN 80 and 100;
SELECT last_name name,salary,manager_id FROM employees WHERE manager_id in (100,101,110);
SELECT DISTINCT manager_id FROM employees;```