ORA-28000: the account is locked

最近两个朋友问我同样的问题，他们发现数据库里面有一个账户总是莫名其妙的被锁住，不知道是什么原因。
    我首先想到的是用户default profiles中的failed_login_attempts参数设置问题，然后扩展的问题是这个参数的精确含义及相关值查询。
   测试结果如下：
  
    1. 查询failed_login_attempts参数默认值：
      10g(备注：9i环境中此参数的值为unlimited)
      SQL> conn / as sysdba
       Connected.
       SQL> desc dba_profiles;
        Name                                      Null?    Type
        ----------------------------------------- -------- ----------------------------
        PROFILE                                   NOT NULL VARCHAR2(30)
        RESOURCE_NAME                             NOT NULL VARCHAR2(32)
        RESOURCE_TYPE                                      VARCHAR2(8)
        LIMIT                                              VARCHAR2(40)
      
       SQL> select resource_name, limit from dba_profiles where resource_name = 'FAILED_LOGIN_ATTEMPTS';
      
       RESOURCE_NAME                    LIMIT
       -------------------------------- ----------------------------------------
      FAILED_LOGIN_ATTEMPTS            10
     
       1 rows selected.
    
     2. 模拟账户被锁现象
        (为方便模拟lock现象，修改default profile failed_login_attempts=3 )
        a.修改参数failed_login_attempts=3
          SQL> conn / as sysdba;
          Connected.
          SQL>alter profile default limit failed_login_attempts 3;
          Profile altered.
        
        b.重现错误登陆
          正确登陆
         SQL> connecc_view/ecc@devdb1
          Connected.
          SQL> connecc_view/ecc@devdb1
          Connected.
          第一次登陆失败
         SQL> connecc_view/hh@devdb1
          ERROR:
          ORA-01017: invalid username/password; logon denied
          Warning: You are no longer connected toORACLE.
          第二次登陆失败
         SQL> connecc_view/hh@devdb1
          ERROR:
          ORA-01017: invalid username/password; logon denied
          第三次登陆失败
         SQL> connecc_view/hh@devdb1
          ERROR:
          ORA-01017: invalid username/password; logon denied
          连续3次登陆失败后，账户被锁住了
         SQL> connecc_view/hh@devdb1
          ERROR:
          ORA-28000: the account is locked
        
     3. 解锁
        SQL> conn / as sysdba
         Connected.
         SQL>alter user ecc_view account unlock;
         User altered.
       
     4. 解决方案
           (1) 可以考虑查询应用部署中错误的password或者数据库连接等可能导致错误password的地方，彻底的查询问题所在。
           (2) 修改参数failed_login_attempts=unlimited
              SQL>alter profile default limit failed_login_attempts unlimited;
               Profile altered.              
               SQL> select resource_name, limit from dba_profiles where resource_name = 'FAILED_LOGIN_ATTEMPTS';
              
               RESOURCE_NAME                    LIMIT
               -------------------------------- ----------------------------------------
               FAILED_LOGIN_ATTEMPTS            UNLIMITED
             
     5. 扩展知识点及备注说明
        (1)  Q: FAILED_LOGIN_ATTEMPTS=3 3的含义是什么？是累计失败次数还是连续失败次数？
               A: FAILED_LOGIN_ATTEMPTS=3的含义是从第一次登录失败开始计算，连续登陆失败的次数。而不是累计失败的次数。
                试验如下：
               SQL> connecc_view/ecc@devdb1
                Connected.
                第一次登陆失败
               SQL> connecc_view/hh@devdb1
                ERROR:
                ORA-01017: invalid username/password; logon denied
                Warning: You are no longer connected to ORACLE.
                第二次登陆失败
               SQL> connecc_view/hh@devdb1
                ERROR:
                ORA-01017: invalid username/password; logon denied
                正确登陆
               SQL> connecc_view/ecc@devdb1
                Connected.
                此时不是累计，而是重新计算
                第一次登陆失败
               SQL> connecc_view/hh@devdb1
                ERROR:
                ORA-01017: invalid username/password; logon denied
                Warning: You are no longer connected to ORACLE.
                第二次登陆失败
               SQL> connecc_view/hh@devdb1
                ERROR:
                ORA-01017: invalid username/password; logon denied
                第三次登陆失败
               SQL> connecc_view/hh@devdb1
                ERROR:
               ORA-01017: invalid username/password; logon denied
                三次登陆失败后，账户被锁
               SQL>  connecc_view/ecc@devdb1
                ERROR:
                ORA-28000: the account is locked
              
        (2)  Q: 如何从数据库中查询当前FAILED_LOGIN_ATTEMPTS的值？dba_profiles是限额，并不代表当前值，如果查询当前失败的值怎么查？
               A: select NAME,LCOUNT  from user$，user$为view dba_users的基表，通常可以查询一下试图对应的基表，oracle可能会隐藏一些参数
           
             初始值为0：
             SQL> select NAME,LCOUNT  from user$ where name = 'ECC_VIEW';
                  NAME                               LCOUNT
                  ------------------------------ ----------
                  ECC_VIEW                               0
                
             错误登陆一次后，值为1
            SQL> connecc_view/h@devdb1
                  ERROR:                    
                  ORA-01017: invalid username/password; logon denied
            SQL> select NAME,LCOUNT  from user$ where name = 'ECC_VIEW';  
                  NAME                               LCOUNT
                  ------------------------------ ----------
                  ECC_VIEW                               1
                
             错误登陆2次后，值为2
            SQL> connecc_view/h@devdb1
                  ERROR:                   
                  ORA-01017: invalid username/password; logon denied
             SQL> select NAME,LCOUNT  from user$ where name = 'ECC_VIEW'; 
                  NAME                               LCOUNT
                  ------------------------------ ----------
                  ECC_VIEW                                2
                 
             正确登陆一次后，此值重置为0
            SQL> connecc_view/ecc@devdb1
                  Connected.             
             SQL> select NAME,LCOUNT  from user$ where name = 'ECC_VIEW'; 
                  NAME                               LCOUNT
                  ------------------------------ ----------
                  ECC_VIEW                               0