oracle database 12cr2 的 sys_context 函数详解数据库

sys_context虽然用的地方不多，但是十分强大，属于oracle的系统函数。归属于STANDARD 包

SQL> select * from v$version ; 
 
BANNER                                           CON_ID 
-------------------------------------------------------------------------------- ---------- 
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production          0 
PL/SQL Release 12.2.0.1.0 - Production                            0 
CORE    12.2.0.1.0  Production                                0 
TNS for Linux: Version 12.2.0.1.0 - Production                        0 
NLSRTL Version 12.2.0.1.0 - Production                            0 
 
SQL> select * from v$database ; 
SQL> select * from v$thread ; 
SQL> select * from gv$instance ;

查找 sys_context 的出处

select * 
from dba_source vs 
where 1=1 
and upper(vs.text) like '%SYS_CONTEXT%' 
and vs.name = 'STANDARD' 
order by vs.line 
; 
 
 
 
  -- New built-in function SYS_CONTEXT 
  function SYS_CONTEXT (namespace varchar2, attribute varchar2) 
    return varchar2; 
 
 -- SYS_CONTEXT now has an additional optional parameter 
  function SYS_CONTEXT(namespace varchar2, attribute varchar2, 
                       newoptional varchar2) 
    return varchar2;   

常用的几个

select SYS_CONTEXT('USERENV','CURRENT_SCHEMA') 
from dual 
; 
select SYS_CONTEXT('USERENV','SESSION_USER') 
from dual 
; 
select SYS_CONTEXT('USERENV','CURRENT_USER') 
from dual 
; 
select SYS_CONTEXT('USERENV','SID') 
from dual 
; 
select SYS_CONTEXT('USERENV','CDB_NAME') 
from dual 
; 
select SYS_CONTEXT('USERENV','CLIENT_IDENTIFIER') 
from dual 
; 
select SYS_CONTEXT('USERENV','CLIENT_INFO') 
from dual 
; 
select SYS_CONTEXT('USERENV','DATABASE_ROLE') 
from dual 
; 
select SYS_CONTEXT('USERENV','DB_DOMAIN') 
from dual 
; 
select SYS_CONTEXT('USERENV','DB_NAME') 
from dual 
; 
select SYS_CONTEXT('USERENV','DB_UNIQUE_NAME') 
from dual 
; 
select SYS_CONTEXT('USERENV','HOST') 
from dual 
; 
select SYS_CONTEXT('USERENV','INSTANCE') 
from dual 
; 
select SYS_CONTEXT('USERENV','INSTANCE_NAME') 
from dual 
; 
select SYS_CONTEXT('USERENV','IP_ADDRESS') 
from dual 
; 
select SYS_CONTEXT('USERENV','ISDBA') 
from dual 
; 
select SYS_CONTEXT('USERENV','LANG') 
from dual 
;

参考:
IT虾米网