SYS_CONTEXT

Syntax

sys_context::=

Text description of sys_context

Purpose

SYS_CONTEXT returns the value of parameter associated with the context namespace. You can use this function in both SQL and PL/SQL statements.

Note: SYS_CONTEXT returns session attributes. Therefore, you cannot use it in parallel queries or in an Real Application Clusters environment.

For namespace and parameter, you can specify either a string (constant) or an expression that resolves to a string designating a namespace or an attribute. The context namespace must already have been created, and the associated parameter and its value must also have been set using the DBMS_SESSION.set_context procedure. The namespace must be a valid SQL identifier. The parameter name can be any string. It is not case sensitive, but it cannot exceed 30 bytes in length.

The datatype of the return value is VARCHAR2. The default maximum size of the return value is 256 bytes. You can override this default by specifying the optional length parameter. The valid range of values is 1 to 4000 bytes. (If you specify an invalid value, Oracle ignores it and uses the default.)

Oracle9i provides a built-in namespace called USERENV, which describes the current session. The predefined parameters of namespace USERENV are listed Table 6-10, along with the lengths of their return strings.

See Also: Oracle9i Application Developer's Guide - Fundamentals for information on using the application context feature in your application development CREATE CONTEXT for information on creating user-defined context namespaces Oracle9i Supplied PL/SQL Packages and Types Reference for information on the DBMS_SESSION.set_context procedure

Examples

The following statement returns the name of the user who logged onto the database:

CONNECT OE/OE
SELECT SYS_CONTEXT ('USERENV', 'SESSION_USER') 
   FROM DUAL;

SYS_CONTEXT ('USERENV', 'SESSION_USER')
------------------------------------------------------
OE

The following hypothetical example returns the group number that was set as the value for the attribute group_no in the PL/SQL package that was associated with the context hr_apps when hr_apps was created:

SELECT SYS_CONTEXT ('hr_apps', 'group_no') "User Group" 
   FROM DUAL;

Table 6-10 Predefined Parameters of Namespace USERENV

Parameter	Return Value	Return Length (bytes)
AUDITED_CURSORID	Returns the cursor ID of the SQL that triggered the audit.	NA
AUTHENTICATION_DATA	Data being used to authenticate the login user. For X.503 certificate authenticated sessions, this field returns the context of the certificate in HEX2 format.	256
	Note: You can change the return value of the AUTHENTICATION_DATA attribute using the length parameter of the syntax. Values of up to 4000 are accepted. This is the only attribute of USERENV for which Oracle implements such a change.
AUTHENTICATION_TYPE	How the user was authenticated: DATABASE: username/password authentication OS: operating system external user authentication NETWORK: network protocol or ANO authentication PROXY: OCI proxy connection authentication	30
BG_JOB_ID	Job ID of the current session if it was established by an Oracle background process. Null if the session was not established by a background process.	30
CLIENT_IDENTIFIER	Returns the client session identifier in the global context--that is, the globally accessed application context or (in the OCI context) the OCI_ATTR_CLIENT_IDENTIFIER attribute. If no globally relevant identifier has been set, returns NULL.	64
CLIENT_INFO	Returns up to 64 bytes of user session information that can be stored by an application using the DBMS_APPLICATION_INFO package.	64
CURRENT_SCHEMA	Name of the default schema being used in the current schema. This value can be changed during the session with an ALTER SESSION SET CURRENT_SCHEMA statement.	30
CURRENT_SCHEMAID	Identifier of the default schema being used in the current session.	30
CURRENT_SQL	Returns the current SQL that triggered the fine-grained auditing event. You can specify this attribute only inside the event handler for the Fine-Grained Auditing feature.	64
CURRENT_USER	The name of the user whose privilege the current session is under.	30
CURRENT_USERID	User ID of the user whose privilege the current session is under	30
DB_DOMAIN	Domain of the database as specified in the DB_DOMAIN initialization parameter.	256
DB_NAME	Name of the database as specified in the DB_NAME initialization parameter	30
ENTRYID	The available auditing entry identifier. You cannot use this attribute in distributed SQL statements. To use this keyword in USERENV, the initialization parameter AUDIT_TRAIL must be set to true.	30
EXTERNAL_NAME	External name of the database user. For SSL authenticated sessions using v.503 certificates, this field returns the distinguished name (DN) stored in the user certificate.	256
FG_JOB_ID	Job ID of the current session if it was established by a client foreground process. Null if the session was not established by a foreground process.	30
GLOBAL_CONTEXT_MEMORY	Returns the number being used in the System Global Area by the globally accessed context.	NA
HOST	Name of the host machine from which the client has connected.	54
INSTANCE	The instance identification number of the current instance.	30
IP_ADDRESS	IP address of the machine from which the client is connected.	30
ISDBA	Returns TRUE if the user has been authenticated as having DBA privileges either through the operating system or through a password file.	30
LANG	The ISO abbreviation for the language name, a shorter form than the existing 'LANGUAGE' parameter.	62
LANGUAGE	The language and territory currently used by your session, along with the database character set, in this form: language_territory.characterset	52
NETWORK_PROTOCOL	Network protocol being used for communication, as specified in the 'PROTOCOL=protocol' portion of the connect string.	256
NLS_CALENDAR	The current calendar of the current session.	62
NLS_CURRENCY	The currency of the current session.	62
NLS_DATE_FORMAT	The date format for the session.	62
NLS_DATE_LANGUAGE	The language used for expressing dates.	62
NLS_SORT	BINARY or the linguistic sort basis.	62
NLS_TERRITORY	The territory of the current session.	62
OS_USER	Operating system username of the client process that initiated the database session	30
PROXY_USER	Name of the database user who opened the current session on behalf of SESSION_USER.	30
PROXY_USERID	Identifier of the database user who opened the current session on behalf of SESSION_USER.	30
SESSION_USER	Database user name by which the current user is authenticated. This value remains the same throughout the duration of the session.	30
SESSION_USERID	Identifier of the database user name by which the current user is authenticated.	30
SESSIONID	The auditing session identifier. You cannot use this attribute in distributed SQL statements.	30
TERMINAL	The operating system identifier for the client of the current session. In distributed SQL statements, this attribute returns the identifier for your local session. In a distributed environment, this is supported only for remote SELECT statements, not for remote INSERT, UPDATE, or DELETE operations. (The return length of this parameter may vary by operating system.)	10