[20260717]ORA-02011 duplicate database link name.txt

--//在centos 9，IP=192.168.56.103上建立dblink，报ORA-02011 duplicate database link name错误,做一个记录：

1.环境：
SCOTT@book01p> @ ver2
==============================
PORT_STRING                   : x86_64/Linux 2.4.xx
VERSION                       : 21.0.0.0.0
BANNER                        : Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production
BANNER_FULL                   : Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production
Version 21.3.0.0.0
BANNER_LEGACY                 : Oracle Database 21c Enterprise Edition Release 21.0.0.0.0 - Production
CON_ID                        : 0
PL/SQL procedure successfully completed.

2.建立dblink：

SYS@book01p> CREATE PUBLIC DATABASE LINK CENTTEST CONNECT TO SCOTT IDENTIFIED BY book USING '192.168.56.101:1521/book01p';
CREATE PUBLIC DATABASE LINK CENTTEST CONNECT TO SCOTT IDENTIFIED BY book USING '192.168.56.101:1521/book01p'
                            *
ERROR at line 1:
ORA-02011: duplicate database link name

SYS@book01p> CREATE PUBLIC DATABASE LINK CENT101 CONNECT TO SCOTT IDENTIFIED BY book USING '192.168.56.101:1521/book01p';
Database link created.

SCOTT@book01p> drop PUBLIC DATABASE LINK CENT101;
Database link dropped.
--//建立dblink CENT101成功，而建立dblink CENTTEST失败、

SCOTT@book01p> select * from v$dblink;
no rows selected

SCOTT@book01p> select * from gv$dblink;
no rows selected
--//奇怪查询gv$dblink视图查询不到结果，仔细检查才发现仅仅使用后gv$dblink才有记录。

SCOTT@book01p> select sysdate from dual@loopback ;
SYSDATE
-------------------
2026-07-18 10:24:42
--//注：该loopback dblink也已经建立。

SCOTT@book01p> select * from gv$dblink;

   INST_ID DB_LINK                          OWNER_ID LOG HET PROTOC OPEN_CURSORS IN_ UPD COMMIT_POINT_STRENGTH     CON_ID
---------- ------------------------------ ---------- --- --- ------ ------------ --- --- --------------------- ----------
         1 LOOPBACK                              109 YES YES UNKN              0 YES NO                      1          3

--//查询底层的视图是sys.link$。对应dba视图是DBA_DB_LINKS。
SYS@book01p> @ col_list sys.link$ PASSWORDX n

SELECT
 owner#
,name
,ctime
,host
,userid
,password
,flag
,authusr
,authpwd
,authpwdx
,credname
,credowner
,acredname
,acredowner
FROM sys.link$

SYS@book01p> @ pr
==============================
OWNER#                        : 1
NAME                          : CENTTEST
CTIME                         : 2026-06-28 11:08:25
HOST                          : 192.168.56.101/book01p
USERID                        : SCOTT
PASSWORD                      :
FLAG                          : 2
AUTHUSR                       :
AUTHPWD                       :
AUTHPWDX                      :
CREDNAME                      :
CREDOWNER                     :
ACREDNAME                     :
ACREDOWNER                    :
==============================
OWNER#                        : 1
NAME                          : LOOPBACK
CTIME                         : 2026-07-17 18:11:44
HOST                          : 127.0.0.1/BOOK01p
USERID                        : SCOTT
PASSWORD                      :
FLAG                          : 2
AUTHUSR                       :
AUTHPWD                       :
AUTHPWDX                      :
CREDNAME                      :
CREDOWNER                     :
ACREDNAME                     :
ACREDOWNER                    :
PL/SQL procedure successfully completed.

--//可以发现centtest dblink 2026-06-28 11:08:25已经建立，主要问题在于自己查询了错误的视图。

SCOTT@book01p> select * from DBA_DB_LINKS;
OWNER   DB_LINK   USERNAME  CREDENTIAL_NAME CREDENTIAL_OWNER HOST                   CREATED            HID SHA VAL INT
------- --------- --------- --------------- ---------------- ---------------------- ------------------ --- --- --- ---
PUBLIC  CENTTEST  SCOTT                                      192.168.56.101/book01p 2026-06-28 11:08:2 NO  NO  YES NO
PUBLIC  LOOPBACK  SCOTT                                      127.0.0.1/BOOK01p      2026-07-17 18:11:4 NO  NO  YES NO