employee.employee_name FROM employee LEFT JOIN salary USING( employee_id ) WHERE salary.salary_amount IS NULL
常两个栏位名称相同时可以USING 不同时可以ON 例如: employee.employee_name FROM employee LEFT JOIN salary ON employee.employee_id=salary.employee_id WHERE salary.salary_amount IS NULL ------------------------------------ 欢迎光临偶像剧场∠(^_^)