故障介绍：
ORA-01017: invalid username/password; logon denied
ORA-02063: preceding line from
分析错误：
从错误信息来看，是用户名和密码的错误，但是用户名和密码我确定没有问题，能够通过密码进行访问数据库。
详细回顾及出现问题及排错思路如下:
创建dblink使用的用户/密码是正确的。
SQL> conn prudent/woo@woo
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
Connected as woo
创建dblink的数据库版本：
SQL> select * from V$VERSION;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production
CORE 10.2.0.4.0 Production
TNS for Linux: Version 10.2.0.4.0 -Production
NLSRTL Version 10.2.0.4.0 - Production
ORACLE 10.2.0.4中创建到 Oracle 11.2.0.3.0 的DBLINK，创建成功
SQL> create database link woo_100
2 connect to prudent
3 identified by woo
4 using '(DESCRIPTION =
5 (ADDRESS_LIST =
6 (ADDRESS = (PROTOCOL =TCP)(HOST = 192.168.0.100)(PORT = 1521))
7 )
8 (CONNECT_DATA =
9 (SERVER = DEDICATED)
10 (SID = woo)
11 )
12 )';
但使用dblink去访问目标数据库时出错
QL> select sysdate from dual@woo;
select sysdate from dual@woo
ORA-01017: invalid username/password; logondenied
ORA-02063: preceding line from woo_100