public synonym 和private synonym 可以同名

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如果public synonym 和private synonym同名，优先访问private synonym；

SQL> select count(1) from user_tables;

COUNT(1)
----------
18

SQL> select count(1) from user_indexes;

COUNT(1)
----------
4
--基于user_tables和user_indexes创建同名的private synonym和public synonym

--private synoym
SQL> create synonym t_private_synonym for user_tables;
Synonym created

--public synonym

SQL> create public synonym t_private_synonym for user_indexes;
Synonym created

SQL> select owner, synonym_name, table_name
2 from dba_synonyms t
3 where t.synonym_name = upper('t_private_synonym');

OWNER                          SYNONYM_NAME                   TABLE_NAME
------------------------------ ------------------------------ ------------------------------
PUBLIC                         T_PRIVATE_SYNONYM              USER_INDEXES
REPORT                         T_PRIVATE_SYNONYM              USER_TABLES

--优先访问private synonym

SQL> select count(1) from t_private_synonym;

COUNT(1)
----------
18

SQL> drop synonym t_private_synonym;

Synonym dropped
--删掉privte synonym后，访问public synonym

SQL> select count(1) from t_private_synonym;

COUNT(1)
----------
4