Oracle小知识集锦

Oracle删除后的恢复

savepoint a;

delete from student ;

rollback to a;

Oracle中修改日期格式

alter session set nls_date_format='yyyy-mm-dd'

Oracle中查询字段为空或不为空的记录

select * from student where birthday is null

select * from student where birthday is not null

删除配置文件

drop profile a [cascade]

alter user xh account unlock：为用户解锁

限制用户登录失败的次数

1.建立配置文件，用户登录失败三次就锁二天，黑体为关键字：

create profile a limit failed_login_attempts 3 password_lock_time 2

2.把这个配置文件运用到用户xh

alter user xh profile a