SYS_CONTEXT
The SYS_CONTEXT function is able to return the following host and IP address information for the current session:
- TERMINAL - An operating system identifier for the current session. This is often the client machine name.
- HOST - The host name of the client machine.
- IP_ADDRESS - The IP address of the client machine.
- SERVER_HOST - The host name of the server running the database instance.
The following examples show the typical output for each variant.
SQL> SELECT SYS_CONTEXT('USERENV','TERMINAL') FROM dual;
SYS_CONTEXT('USERENV','TERMINAL')
--------------------------------------------------------------------
marge
1 row selected.
SQL> SELECT SYS_CONTEXT('USERENV','HOST') FROM dual;
SYS_CONTEXT('USERENV','HOST')
--------------------------------------------------------------------
marge
1 row selected.
SQL> SELECT SYS_CONTEXT('USERENV','IP_ADDRESS') FROM dual;
SYS_CONTEXT('USERENV','IP_ADDRESS')
--------------------------------------------------------------------
192.168.2.3
1 row selected.
SQL> SELECT SYS_CONTEXT('USERENV','SERVER_HOST') FROM dual;
SYS_CONTEXT('USERENV','SERVER_HOST')
--------------------------------------------------------------------
C4210gr2
1 row selected.
The Oracle/PLSQL SYS_CONTEXT function can be used to retrieve information about the Oracle environment.
Syntax
The syntax for the Oracle/PLSQL SYS_CONTEXT function is:
SYS_CONTEXT( namespace, parameter, [ length ] )
Parameters or Arguments
namespace is an Oracle namespace that has already been created. If the namespace of 'USERENV' is used, attributes describing the current Oracle session can be returned. parameter is a valid attribute that has been set using the DBMS_SESSION.set_context procedure. length is optional. It is the length of the return value in bytes. If this parameter is omitted or if an invalid entry is provided, the sys_context function will default to 256 bytes.
Note
The valid parameters for the namespace called 'USERENV' are as follows: (Note that not all parameters are valid in all versions of Oracle)
Parameter
|
Explanation
|
Oracle 9i
|
Oracle 10g
|
Oracle 11g
|
ACTION
|
Returns the position in the module
|
No
|
Yes
|
Yes
|
AUDITED_CURSORID
|
Returns the cursor ID of the SQL that triggered the audit
|
Yes
|
Yes
|
Yes
|
AUTHENTICATED_IDENTITY
|
Returns the identity used in authentication
|
No
|
Yes
|
Yes
|
AUTHENTICATION_DATA
|
Authentication data
|
Yes
|
Yes
|
Yes
|
AUTHENTICATION_METHOD
|
Returns the method of authentication
|
No
|
Yes
|
Yes
|
AUTHENTICATION_TYPE
|
Describes how the user was authenticated. Can be one of the following values: Database, OS, Network, or Proxy
|
Yes
|
No
|
No
|
BG_JOB_ID
|
If the session was established by an Oracle background process, this parameter will return the Job ID. Otherwise, it will return NULL.
|
Yes
|
Yes
|
Yes
|
CLIENT_IDENTIFIER
|
Returns the client identifier (global context)
|
Yes
|
Yes
|
Yes
|
CLIENT_INFO
|
User session information
|
Yes
|
Yes
|
Yes
|
CURRENT_BIND
|
Bind variables for fine-grained auditing
|
No
|
Yes
|
Yes
|
CURRENT_SCHEMA
|
Returns the default schema used in the current schema
|
Yes
|
Yes
|
Yes
|
CURRENT_SCHEMAID
|
Returns the identifier of the default schema used in the current schema
|
Yes
|
Yes
|
Yes
|
CURRENT_SQL
|
Returns the SQL that triggered the audit event
|
Yes
|
Yes
|
Yes
|
CURRENT_SQL_LENGTH
|
Returns the length of the current SQL statement that triggered the audit event
|
No
|
Yes
|
Yes
|
CURRENT_USER
|
Name of the current user
|
Yes
|
No
|
No
|
CURRENT_USERID
|
Userid of the current user
|
Yes
|
No
|
No
|
DB_DOMAIN
|
Domain of the database from the DB_DOMAIN initialization parameter
|
Yes
|
Yes
|
Yes
|
DB_NAME
|
Name of the database from the DB_NAME initialization parameter
|
Yes
|
Yes
|
Yes
|
DB_UNIQUE_NAME
|
Name of the database from the DB_UNIQUE_NAME initialization parameter
|
No
|
Yes
|
Yes
|
ENTRYID
|
Available auditing entry identifier
|
Yes
|
Yes
|
Yes
|
ENTERPRISE_IDENTITY
|
Returns the user's enterprise-wide identity
|
No
|
Yes
|
Yes
|
EXTERNAL_NAME
|
External of the database user
|
Yes
|
No
|
No
|
FG_JOB_ID
|
If the session was established by a client foreground process, this parameter will return the Job ID. Otherwise, it will return NULL.
|
Yes
|
Yes
|
Yes
|
GLOBAL_CONTEXT_MEMORY
|
The number used in the System Global Area by the globally accessed context
|
Yes
|
Yes
|
Yes
|
GLOBAL_UID
|
The global user ID from Oracle Internet Directory for enterprise security logins. Returns NULL for all other logins.
|
No
|
No
|
Yes
|
HOST
|
Name of the host machine from which the client has connected
|
Yes
|
Yes
|
Yes
|
IDENTIFICATION_TYPE
|
Returns the way the user's schema was created
|
No
|
Yes
|
Yes
|
INSTANCE
|
The identifier number of the current instance
|
Yes
|
Yes
|
Yes
|
INSTANCE_NAME
|
The name of the current instance
|
No
|
Yes
|
Yes
|
IP_ADDRESS
|
IP address of the machine from which the client has connected
|
Yes
|
Yes
|
Yes
|
ISDBA
|
Returns TRUE if the user has DBA privileges. Otherwise, it will return FALSE.
|
Yes
|
Yes
|
Yes
|
LANG
|
The ISO abbreviate for the language
|
Yes
|
Yes
|
Yes
|
LANGUAGE
|
The language, territory, and character of the session. In the following format:
language_territory.characterset
|
Yes
|
Yes
|
Yes
|
MODULE
|
Returns the appplication name set through DBMS_APPLICATION_INFO package or OCI
|
No
|
Yes
|
Yes
|
NETWORK_PROTOCOL
|
Network protocol used
|
Yes
|
Yes
|
Yes
|
NLS_CALENDAR
|
The calendar of the current session
|
Yes
|
Yes
|
Yes
|
NLS_CURRENCY
|
The currency of the current session
|
Yes
|
Yes
|
Yes
|
NLS_DATE_FORMAT
|
The date format for the current session
|
Yes
|
Yes
|
Yes
|
NLS_DATE_LANGUAGE
|
The language used for dates
|
Yes
|
Yes
|
Yes
|
NLS_SORT
|
BINARY or the linguistic sort basis
|
Yes
|
Yes
|
Yes
|
NLS_TERRITORY
|
The territory of the current session
|
Yes
|
Yes
|
Yes
|
OS_USER
|
The OS username for the user logged in
|
Yes
|
Yes
|
Yes
|
POLICY_INVOKER
|
The invoker of row-level security policy functions
|
No
|
Yes
|
Yes
|
PROXY_ENTERPRISE_IDENTITY
|
The Oracle Internet Directory DN when the proxy user is an enterprise user
|
No
|
Yes
|
Yes
|
PROXY_GLOBAL_UID
|
The global user ID from Oracle Internet Directory for enterprise user security proxy users. Returns NULL for all other proxy users.
|
No
|
Yes
|
Yes
|
PROXY_USER
|
The name of the user who opened the current session on behalf of SESSION_USER
|
Yes
|
Yes
|
Yes
|
PROXY_USERID
|
The identifier of the user who opened the current session on behalf of SESSION_USER
|
Yes
|
Yes
|
Yes
|
SERVER_HOST
|
The host name of the machine where the instance is running
|
No
|
Yes
|
Yes
|
SERVICE_NAME
|
The name of the service that the session is connected to
|
No
|
Yes
|
Yes
|
SESSION_USER
|
The database user name of the user logged in
|
Yes
|
Yes
|
Yes
|
SESSION_USERID
|
The database identifier of the user logged in
|
Yes
|
Yes
|
Yes
|
SESSIONID
|
The identifier of the auditing session
|
Yes
|
Yes
|
Yes
|
SID
|
Session number
|
No
|
Yes
|
Yes
|
STATEMENTID
|
The auditing statement identifier
|
No
|
Yes
|
Yes
|
TERMINAL
|
The OS identifier of the current session
|
Yes
|
Yes
|
Yes
|
Applies To
The SYS_CONTEXT function can be used in the following versions of Oracle/PLSQL:
· Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i, Oracle 8i
Example
Let's look at some Oracle SYS_CONTEXT function examples and explore how you would use the SYS_CONTEXT function in Oracle/PLSQL.
For example:
SYS_CONTEXT('USERENV', 'NLS_DATE_FORMAT')
|
would return 'RR-MM-DD'
|
SYS_CONTEXT('USERENV', 'NLS_SORT')
|
would return 'BINARY'
|
