测试zx用户，使用错误的密码连接11次
[oracle@rhel6 ~]$ cat login.sh?
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
sqlplus zx/123 <EOF
[oracle@rhel6 ~]$ sh login.sh
?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:16 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:16 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:16 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:16 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:17 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:19 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:22 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:26 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:31 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:37 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-01017: invalid username/password; logon denied
?
?
Enter user-name:?
SQL*Plus: Release 11.2.0.4.0 Production on Mon Jan 16 17:09:45 2017
?
Copyright (c) 1982, 2013, Oracle.? All rights reserved.
?
ERROR:
ORA-28000: the account is locked
#提示用户被锁定
#查询视图zx用户被锁定
sys@ORCL>select username,account_status,profile from dba_users where username='ZX';
?
USERNAME? ACCOUNT_STATUS? ? PROFILE
---------- -------------------- ---------------
ZX? ? OPEN? ? ? ? DEFAULT

基于这个特性，如果在生产上修改了数据库用户密码，但是应用部分没有修改完全，则应用启动后有问题的应用会一直尝试连接数据库导致数据库用户被锁定，影响业务正常运行。可以修改用户尝试登录次数为ulimited来防止这种情况发生。
12345678910111213 sys@ORCL>alter user zx account unlock;
?
User altered.
?
sys@ORCL>alter profile default limit failed_login_attempts unlimited;
?
Profile altered.
?
sys@ORCL>select * from dba_profiles where profile='DEFAULT' and resource_name='FAILED_LOGIN_ATTEMPTS';
?
PROFILE? ? RESOURCE_NAME? ? ? ? ? ? ? RESOURCE_TYPE? ? LIMIT
--------------- ------------------------------ ------------------------ -------------------
DEFAULT? ? FAILED_LOGIN_ATTEMPTS? ? ? ? ? PASSWORD? ? ? ? UNLIMITED

至此，用户zx无论使用多少次错误密码都不会导致账户锁定。