经常遇到需要查找某个对象的定义的情况，下面针对不同类型的对象分别讨论：
一、V$视图和X$视图
普通用户不能访问V$视图：
SQL> conn lunar/lunar@test1
已连接。
SQL> select * from user_sys_privs;
USERNAME PRIVILEGE ADMIN_OPTION
------------------------------ ---------------------------------------- ------------
SQL> select * from user_role_privs;
USERNAME GRANTED_ROLE ADMIN_OPTION DEFAULT_ROLE OS_GRANTED
------------------------------ ------------------------------ ------------ ------------ ----------
LUNAR CONNECT NO YES NO
LUNAR RESOURCE NO YES NO
PUBLIC PLUSTRACE NO YES NO
SQL> select count(*) from v$fixed_table;
select count(*) from v$fixed_table
ORA-00942: 表或视图不存在
必须授权：
SQL> conn /@test1 as sysdba
已连接。
SQL> grant select on v_$fixed_table to lunar;
授权成功。
SQL> conn lunar/lunar@test1
已连接。
SQL>
得到授权的普通用户仍然只能访问V$开头的视图，而不能直接访问V_$开头的视图，
因为实际上V$视图是V_$视图的公有同义词（PUBLIC SYNONYM）
要想访问V_$必须带上SYS.V_$，例如
SQL> select count(*) from v$fixed_table;
COUNT(*)
----------
912
SQL> select count(*) from v_$fixed_table;
select count(*) from v_$fixed_table
ORA-00942: 表或视图不存在
SQL> select count(*) from sys.v_$fixed_table;
COUNT(*)
----------
912
SQL>
也可以授予用户SELECT any table权限，这样这个用户就可以访问所有的V$视图了：
SQL> grant select any table to lunar;
授权成功。
SQL> select * from user_role_privs;
USERNAME GRANTED_ROLE ADMIN_OPTION DEFAULT_ROLE OS_GRANTED
------------------------------ ------------------------------ ------------ ------------ ----------
LUNAR CONNECT NO YES NO
LUNAR RESOURCE NO YES NO
PUBLIC PLUSTRACE NO YES NO
SQL> select * from user_sys_privs;
USERNAME PRIVILEGE ADMIN_OPTION
------------------------------ ---------------------------------------- ------------
LUNAR SELECT ANY TABLE NO
SQL> select count(*) from v$fixed_table;
COUNT(*)
----------
912
SQL> select * from v$fixed_table where rownum<2;
NAME OBJECT_ID TYPE TABLE_NUM
------------------------------ ---------- ----- ----------
X$KQFTA 4294950912 TABLE 0
SQL> select * from v_$fixed_table where rownum<2;
select * from v_$fixed_table where rownum<2
ORA-00942: 表或视图不存在
SQL> select * from sys.v_$fixed_table where rownum<2;
NAME OBJECT_ID TYPE TABLE_NUM
------------------------------ ---------- ----- ----------
X$KQFTA 4294950912 TABLE 0
SQL>
通过查询V$FIXED_TABLE视图，我们可以看到大部分V$视图和一些X$视图（还有一些ORACLE未公开的视图不在其中）。
那么这些V$视图又是有什么组成的呢？
通过查询V$FIXED_VIEW_DEFINITION视图，可以看到这些V$视图的创建语句
SQL> conn /@test1 as sysdba
已连接。
SQL> grant select any table to lunar;
授权成功。
SQL> conn lunar/lunar@test1
已连接。
SQL>
SQL> set heading off echo off long 50000 pages 10000
SQL> select * from v$fixed_view_definition where view_name='V$FIXED_TABLE';
V$FIXED_TABLE select NAME , OBJECT_ID , TYPE , TABLE_NUM from GV$FIXED_TABLE where inst_id = USERENV('Instance')
SQL>
select NAME , OBJECT_ID , TYPE , TABLE_NUM
from GV$FIXED_TABLE
where inst_id = USERENV('Instance')
那么这个GV$FIXED_TABLE视图的定义又是怎样的呢？
SQL> select * from v$fixed_view_definition where view_name='GV$FIXED_TABLE';
GV$FIXED_TABLE select inst_id,kqftanam, kqftaobj, 'TABLE', indx from x$kqfta union all select inst_id,kqfvinam, kqfviobj, 'VIEW', 65537 from x$kqfvi union all select inst_id,kqfdtnam, kqfdtobj, 'TABLE', 65537 from x$kqfdt
SQL>
select inst_id,kqftanam, kqftaobj, 'TABLE', indx from x$kqfta
union all
select inst_id,kqfvinam, kqfviobj, 'VIEW', 65537 from x$kqfvi
union all
select inst_id,kqfdtnam, kqfdtobj, 'TABLE', 65537 from x$kqfdt
这样我们就找到了创建一个V$视图的最低层的信息，即一个V$视图是由哪些X$表构成的。
要找到底层X$表的索引信息，可以查询v$indexed_fixed_column：
SQL> desc v$indexed_fixed_column
Name Type Nullable Default Comments
--------------- ------------ -------- ------- --------
TABLE_NAME VARCHAR2(30) Y
INDEX_NUMBER NUMBER Y
COLUMN_NAME VARCHAR2(30) Y
COLUMN_POSITION NUMBER Y
SQL>
例如：
SQL> select * from v$indexed_fixed_column where table_name='X$KQFTA';
TABLE_NAME INDEX_NUMBER COLUMN_NAME COLUMN_POSITION
------------------------------ ------------ ------------------------------ ---------------
X$KQFTA 1 ADDR 0
X$KQFTA 2 INDX 0
SQL>
一般来说，V$视图和GV$视图的定义是一样的，只是GV$视图中包含的实例id的信息，常用于OPS或者RAC的系统中，也有少数几个V$视图和GV$视图的定义是有区别的，比如GV$PX_PROCESS和V$PX_PROCESS：
SQL> select * from v$fixed_view_definition where view_name='GV$PX_PROCESS';
GV$PX_PROCESS select a.inst_id, a.kxfpdpnam, decode(bitand(a.kxfpdpflg, 16), 0, 'IN USE', 'AVAILABLE'), b.pid, a.kxfpdpspid, c.sid, c.serial# from x$kxfpdp a, V$PROCESS b, V$SESSION c where bitand(kxfpdpflg, 8) != 0 and a.kxfpdpspid = b.SPID and a.kxfpdpspid = c.PROCESS(+)
SQL>
select a.inst_id, a.kxfpdpnam,
decode(bitand(a.kxfpdpflg, 16), 0, 'IN USE', 'AVAILABLE'),
b.pid, a.kxfpdpspid, c.sid, c.serial#
from x$kxfpdp a, V$PROCESS b, V$SESSION c
where bitand(kxfpdpflg, 8) != 0 and a.kxfpdpspid = b.SPID and a.kxfpdpspid = c.PROCESS(+)
SQL> select * from v$fixed_view_definition where view_name='V$PX_PROCESS';
V$PX_PROCESS select SERVER_NAME, STATUS, PID, SPID, SID, SERIAL# from GV$PX_PROCESS where inst_id = USERENV('Instance')
SQL>
select SERVER_NAME, STATUS, PID, SPID, SID, SERIAL#
from GV$PX_PROCESS
where inst_id = USERENV('Instance')
二、数据字典的组成
如何得到一个数据字典表的定义呢？
SQL> desc dba_views
Name Type Nullable Default Comments
---------------- -------------- -------- ------- -----------------------------------------------------------
OWNER VARCHAR2(30) Owner of the view
VIEW_NAME VARCHAR2(30) Name of the view
TEXT_LENGTH NUMBER Y Length of the view text
TEXT LONG Y View text
TYPE_TEXT_LENGTH NUMBER Y Length of the type clause of the object view
TYPE_TEXT VARCHAR2(4000) Y Type clause of the object view
OID_TEXT_LENGTH NUMBER Y Length of the WITH OBJECT OID clause of the object view
OID_TEXT VARCHAR2(4000) Y WITH OBJECT OID clause of the object view
VIEW_TYPE_OWNER VARCHAR2(30) Y Owner of the type of the view if the view is an object view
VIEW_TYPE VARCHAR2(30) Y Type of the view if the view is an object view
SUPERVIEW_NAME VARCHAR2(30) Y Name of the superview, if view is a subview
SQL>
SQL> set heading off echo off long 1000000000 pages 10000
SQL> select text from dba_views where view_name ='DBA_USERS';
select u.name, u.user#, u.password,
m.status,
decode(u.astatus, 4, u.ltime,
5, u.ltime,
6, u.ltime,
8, u.ltime,
9, u.ltime,
10, u.ltime, to_date(NULL)),
decode(u.astatus,
1, u.exptime,
2, u.exptime,
5, u.exptime,
6, u.exptime,
9, u.exptime,
10, u.exptime,
decode(u.ptime, '', to_date(NULL),
decode(pr.limit#, 2147483647, to_date(NULL),
decode(pr.limit#, 0,
decode(dp.limit#, 2147483647, to_date(NULL), u.ptime +
dp.limit#/86400),
u.ptime + pr.limit#/86400)))),
dts.name, tts.name, u.ctime, p.name, u.defschclass, u.ext_username
from sys.user$ u, sys.ts$ dts, sys.ts$ tts, sys.profname$ p,
sys.user_astatus_map m, sys.profile$ pr, sys.profile$ dp
where u.datats# = dts.ts#
and u.resource$ = p.profile#
and u.tempts# = tts.ts#
and u.astatus = m.status#
and u.type# = 1
and u.resource$ = pr.profile#
and dp.profile# = 0
and dp.type#=1
and dp.resource#=1
and pr.type# = 1
and pr.resource# = 1
SQL>
三、如何查找用户自定义的某个表的定义？
在Oracle 9i以前，可以使用下面的方法：
SQL> select substr(table_name,1,20) tabname,
2 substr(column_name,1,20)column_name,
3 rtrim(data_type)||'('||data_length||')' from dba_tab_columns
4 where owner='&username'
5 /
TABNAME COLUMN_NAME RTRIM(DATA_TYPE)||'('||DATA_LE
---------------------------------------- ---------------------------------------- --------------------------------------------------------------------------------
BONUS ENAME VARCHAR2(10)
BONUS JOB VARCHAR2(9)
BONUS SAL NUMBER(22)
BONUS COMM NUMBER(22)
DEPT DEPTNO NUMBER(22)
DEPT DNAME VARCHAR2(14)
DEPT LOC VARCHAR2(13)
DUMMY DUMMY NUMBER(22)
EMP EMPNO NUMBER(22)
EMP ENAME VARCHAR2(10)
EMP JOB VARCHAR2(9)
EMP MGR NUMBER(22)
EMP HIREDATE DATE(7)
EMP SAL NUMBER(22)
EMP COMM NUMBER(22)
EMP DEPTNO NUMBER(22)
SALGRADE GRADE NUMBER(22)
SALGRADE LOSAL NUMBER(22)
SALGRADE HISAL NUMBER(22)
19 rows selected
SQL>
从Oracle 9i开始，可以使用dbms_metadata.get_ddl来找到对象的定义，例如：
SQL> @C:/TEMP/get_obj_sql.sql
SQL> set heading off echo off pages 10000 long 90000
输入 object_type 的值: TABLE
输入 object_name 的值: EMP
输入 object_owner 的值: LUNAR
原值 1: select dbms_metadata.get_ddl(upper('&OBJECT_TYPE'),upper('&OBJECT_NAME'),upper('&OBJECT_O
WNER')) from dual
新值 1: select dbms_metadata.get_ddl(upper('TABLE'),upper('EMP'),upper('LUNAR')) from dual
CREATE TABLE "LUNAR"."EMP"
( "EMPNO" NUMBER(4,0) NOT NULL ENABLE,
"ENAME" VARCHAR2(10),
"JOB" VARCHAR2(9),
"MGR" NUMBER(4,0),
"HIREDATE" DATE,
"SAL" NUMBER(7,2),
"COMM" NUMBER(7,2),
"DEPTNO" NUMBER(2,0)
) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
TABLESPACE "SYSTEM"
SQL>
注意，这个查询是需要临时表空间的，所以如果临时表空间不够查询就会有问题了：
SQL> @C:/TEMP/get_obj_sql.sql
SQL> set heading off echo off pages 10000 long 90000
输入 object_type 的值: TABLE
输入 object_name 的值: DEPT
输入 object_owner 的值: LUNAR
原值 1: select dbms_metadata.get_ddl(upper('&OBJECT_TYPE'),upper('&OBJECT_NAME'),upper('&OBJECT_O
WNER')) from dual
新值 1: select dbms_metadata.get_ddl(upper('TABLE'),upper('DEPT'),upper('LUNAR')) from dual
ERROR:
ORA-25153: 临时表空间为空
ORA-06512: 在"SYS.DBMS_LOB", line 424
ORA-06512: 在"SYS.DBMS_METADATA", line 557
ORA-06512: 在"SYS.DBMS_METADATA", line 1221
ORA-06512: 在line 1
未选定行
SQL>
SQL> SELECT NAME FROM V$TEMPFILE;
未选定行
SQL> SELECT NAME FROM V$TABLESPACE;
NAME
------------------------------
SYSTEM
UNDOTBS1
TEMP
INDX
USERS
SQL> ALTER TEMPORARY TABLESPACE TEMP ADD TEMPFILE 'D:/oracle92/oradata/test1/TEMP01.DBF' SIZE 10M;
ALTER TEMPORARY TABLESPACE TEMP ADD TEMPFILE 'D:/oracle92/oradata/test1/TEMP01.DBF' SIZE 10M
*
ERROR 位于第 1 行:
ORA-00940: 无效的 ALTER 命令
SQL> ALTER TABLESPACE TEMP ADD TEMPFILE 'D:/oracle92/oradata/test1/TEMP01.DBF' SIZE 10M;
表空间已更改。
SQL> @C:/TEMP/get_obj_sql.sql
SQL> set heading off echo off pages 10000 long 90000
输入 object_type 的值: TABLE
输入 object_name 的值: EMP
输入 object_owner 的值: LUNAR
原值 1: select dbms_metadata.get_ddl(upper('&OBJECT_TYPE'),upper('&OBJECT_NAME'),upper('&OBJECT_O
WNER')) from dual
新值 1: select dbms_metadata.get_ddl(upper('TABLE'),upper('EMP'),upper('LUNAR')) from dual
CREATE TABLE "LUNAR"."EMP"
( "EMPNO" NUMBER(4,0) NOT NULL ENABLE,
"ENAME" VARCHAR2(10),
"JOB" VARCHAR2(9),
"MGR" NUMBER(4,0),
"HIREDATE" DATE,
"SAL" NUMBER(7,2),
"COMM" NUMBER(7,2),
"DEPTNO" NUMBER(2,0)
) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 NOCOMPRESS LOGGING
STORAGE(INITIAL 65536 NEXT 1048576 MINEXTENTS 1 MAXEXTENTS 2147483645
PCTINCREASE 0 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
TABLESPACE "SYSTEM"
SQL>
SQL>
dbms_metadata.get_ddl也可以用来查询其他对象的创建语句，使用方法如下；
select dbms_metadata.get_ddl('对象类型','对象名','用户名') from dual;
例如：
oracle@cs_db02:/arch1/lunar/tools > get_obj_sql.sh procedure aa misc
Connected.
CREATE OR REPLACE PROCEDURE "MISC"."AA" is
begin
delete from error_tip;
end aa;
oracle@cs_db02:/arch1/lunar/tools >