爲什麼我必須雙引號模式名稱和表名稱才能從Oracle表中查詢？

Question

我是Oracle新手，遇到以下問題。爲什麼我必須雙引號模式名稱和表名稱才能從表中查詢？有什麼設置可以改變它嗎？

謝謝。

SQL> conn sys/ogrish@orcl as sysdba 
Connected. 
SQL> show user 
USER is "SYS" 
SQL> select * from v$version; 

BANNER 
-------------------------------------------------------------------------------- 
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production 
PL/SQL Release 11.2.0.1.0 - Production 
CORE 11.2.0.1.0  Production 
TNS for 64-bit Windows: Version 11.2.0.1.0 - Production 
NLSRTL Version 11.2.0.1.0 - Production 

SQL> select * from m.album; 
select * from m.album 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 


SQL> select * from M.Album where rownum < 2; 
select * from M.Album where rownum < 2; 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 

SQL> select * from "M"."Album" where rownum < 2; 

    AlbumId Title 
---------- ---------------------------------------------------------------------- 
     1 For Those About To Rock We Salute You 

SQL> conn m/m@orcl 
Connected. 
SQL> select table_name from user_tables; 

TABLE_NAME 
------------------------------ 
Album 
Artist 
Customer 
Employee 
Genre 
Invoice 
InvoiceLine 
MediaType 
Playlist 
PlaylistTrack 
sysdiagrams 

TABLE_NAME 
------------------------------ 
Track 

12 rows selected. 

SQL> select * from album where rownum < 2; 
select * from album where rownum < 2; 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 


SQL> select * from Album where rownum < 2; 
select * from Album where rownum < 2 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 


SQL> select * from m.album where rownum < 2; 
select * from m.album where rownum < 2 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 


SQL> select * from M.Album where rownum < 2; 
select * from M.Album where rownum < 2 
       * 
ERROR at line 1: 
ORA-00942: table or view does not exist 


SQL> select * from "M"."Album" where rownum < 2; 

    AlbumId Title 
---------- ---------------------------------------------------------------------- 
     1 For Those About To Rock We Salute You 

SQL> select * from "Album" where rownum < 2; 

    AlbumId Title 
---------- ---------------------------------------------------------------------- 
     1 For Those About To Rock We Salute You 

SQL> 

Answer 1

您不必在架構名稱添加雙引號，但你必須這樣做在桌子上名字，因爲你用引號（這使得它區分大小寫）創造了它：

select * from M."Album" 

也應該工作。否則，默認將M.Album轉換爲M.ALBUM - 並且表ALBUM不存在。

Answer 2

您可以避免使用同義詞預先固定架構名稱。