例如: 简单案例 加演示 --删除数据 --语法:delete from [表名];删除所有数据 --语法:delete from [表名] where [字段1]='字段1的值'and [字段2]='字段2的值' or [字段3]='字段3的值';删除指定数据 delete from heros where age is null --删除年龄为null的人 delete from heros where (age>=40 and age