oracle 用户密码原则

今天在oracle数据库中修改用户密码的时候发现了一个下面的规律

1  密码只由字母组成，创建成功

sql> alter user ics identified by password;

User changed.

2 密码只由数字组成，创建成功

sql> alter user ics identified by 123456;

User changed.

3 密码由字母+数字组成，创建成功

sql> alter user ics identified by password123;

User changed.

4 密码由数字+字母组成，创建失败

sql> alter user ics identified by 1q2w3e;

ERROR at line 1:

ORA-00922: missing or invalid option

5 密码由数字+密码组成时，必须加双引号才能成功

sql> alter user ics identified by "1q2w3e";

User changed.

sql> conn ics/1q2w3e

Connected.

创建用户时候同理