1.group by 和求和函数的使用 select className,SUM(num) as sumNum FROM test GROUP BY className 2.更新一个字段的所有值 update table set 列明=1 相关文章: 2022-01-09 2021-08-22 2021-05-21 2022-12-23 2022-12-23 2022-12-23 2021-05-19 2021-07-11