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'