非等值連接配接

#2、非等值連接配接
#案例1:查詢員工的工資和工資級别
SELECT * FROM `job_grades`;
SELECT `salary`,`employee_id` FROM `employees`;
SELECT `salary`,`grade_level`
FROM `employees` e,`job_grades` j
WHERE `salary`>=`lowest_sal`&&`salary`<=`highest_sal`
&&`grade_level`='A';