如何理解同义词synonym

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--目标库操作：192.168.56.11[oracle@rhel ~]$ sqlplus / as sysdbaSQL*Plus: Release 11.2.0.4.0 Production on Thu Nov 23 17:20:05 2017Copyright (c) 1982, 2013, Oracle.  All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> CONN hr/hr;Connected.SQL>  create table syno as select * from user_objects;Table created.SQL> SQL> select count(*) from syno;  COUNT(*)----------        35--源库操作：192.168.56.12[oracle@wang admin]$ sqlplus / as sysdbaSQL*Plus: Release 11.2.0.4.0 Production on Fri Dec 8 15:40:15 2017Copyright (c) 1982, 2013, Oracle.  All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> conn hr/hr; Connected.SQL> select * from tab;TNAME                          TABTYPE  CLUSTERID------------------------------ ------- ----------B_FILE_PACKAGE                 TABLEB_PACKAGE_STATE_TRANS          TABLECOUNTRIES                      TABLEDEPARTMENTS                    TABLEEMPLOYEES                      TABLEEMPLOYEES_BAK                  TABLEEMP_DETAILS_VIEW               VIEWJOBS                           TABLEJOB_HISTORY                    TABLELOCATIONS                      TABLEREGIONS                        TABLE11 rows selected.SQL> create database link ora connect to hr identified by hr using orcl;Database link created.SQL> create synonym co for syno@ora;Synonym created.SQL> create synonym coe  for hr.syno@ora;Synonym created.SQL> select count(*) from co;  COUNT(*)----------        35SQL>   select count(*) from coe;  COUNT(*)----------35SQL> desc co        Name                                      Null?    Type----------------------------------------- -------- ----------------------------OBJECT_NAME                                        VARCHAR2(128) SUBOBJECT_NAME                                     VARCHAR2(30)OBJECT_ID                                          NUMBER DATA_OBJECT_ID                                     NUMBEROBJECT_TYPE                                        VARCHAR2(19)CREATED                                            DATE LAST_DDL_TIME                                      DATETIMESTAMP                                          VARCHAR2(19) STATUS                                             VARCHAR2(7)TEMPORARY                                          VARCHAR2(1)GENERATED                                          VARCHAR2(1) SECONDARY                                          VARCHAR2(1)NAMESPACE                                          NUMBER EDITION_NAME                                       VARCHAR2(30)SQL> SQL> desc coe Name                                      Null?    Type----------------------------------------- -------- ----------------------------OBJECT_NAME                                        VARCHAR2(128) SUBOBJECT_NAME                                     VARCHAR2(30)OBJECT_ID                                          NUMBER DATA_OBJECT_ID                                     NUMBEROBJECT_TYPE                                        VARCHAR2(19)CREATED                                            DATE LAST_DDL_TIME                                      DATETIMESTAMP                                          VARCHAR2(19) STATUS                                             VARCHAR2(7)TEMPORARY                                          VARCHAR2(1)GENERATED                                          VARCHAR2(1) SECONDARY                                          VARCHAR2(1)NAMESPACE                                          NUMBER EDITION_NAME                                       VARCHAR2(30)SQL> select object_name,object_id,object_type,status from co where rownum <=2;OBJECT_NAM  OBJECT_ID OBJECT_TYPE                            STATUS---------- ---------- -------------------------------------- --------------REGIONS         51846 TABLE                                  VALIDREG_ID_PK       51847 INDEX                                  VALIDSQL> select object_name,object_id,object_type,status from coe where rownum <=2;OBJECT_NAM  OBJECT_ID OBJECT_TYPE                            STATUS---------- ---------- -------------------------------------- --------------REGIONS         51846 TABLE                                  VALIDREG_ID_PK       51847 INDEX                                  VALIDSQL> [oracle@wang admin]$ cat tnsnames.ora# tnsnames.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/tnsnames.ora# Generated by Oracle configuration tools.orcl =(DESCRIPTION =    (LOAD_BALANCE = yes)    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.11)(PORT = 1521))    (CONNECT_DATA =(SERVICE_NAME = orcl)    )  )[oracle@wang admin]$ [oracle@wang admin]$ tnsping orclTNS Ping Utility for Linux: Version 11.2.0.4.0 - Production on 08-DEC-2017 17:27:17Copyright (c) 1997, 2013, Oracle.  All rights reserved.Used parameter files:Used TNSNAMES adapter to resolve the aliasAttempting to contact (DESCRIPTION = (LOAD_BALANCE = yes) (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.56.11)(PORT = 1521)) (CONNECT_DATA = (SERVICE_NAME = orcl)))OK (10 msec)[oracle@wang admin]$ SQL> select OWNER,SYNONYM_NAME,TABLE_OWNER,TABLE_NAME,DB_LINK from dba_synonyms where SYNONYM_NAME in (CO11,COE11);OWNER                          SYNONYM_NAME                   TABLE_OWNER                    TABLE_NAME                     DB_LINK------------------------------ ------------------------------ ------------------------------ ------------------------------ ---------------HR                             CO                                                            SYNO                           ORAHR                             COE                            HR                             SYNO                           ORASQL> col HOST for a20SQL> select * from dba_db_links where DB_LINK=ORA;OWNER                          DB_LINK         USERNAME                       HOST                 CREATED------------------------------ --------------- ------------------------------ -------------------- ------------HR                             ORA             HR                             orcl                 08-DEC-17查询验证完全相同，连个同义词co和coe！

以上就是如何理解同义词synonym，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注行业资讯频道。