行子查询(结果集一行多列或多行多列)
#案例:查询员工编号最小并且工资最高的员工信息
#①查询最小的员工编号
SELECT MIN(employee_id)FROM employees
#②查询最高工资
SELECT MAX(salary)FROM employees
#③查询员工信息
SELECT *FROM employeesWHERE employee_id=(SELECT MIN(employee_id)FROMemployees)AND salary=(SELECT MAX(salary)FROMemployees);
#另一种写法
SELECT * FROM employeesWHERE (employee_id,salary)=(SELECT MIN(employee_id),MAX(salary)FROM employees);