SYS_CONTEXT

Syntax

Purpose

SYS_CONTEXT returns the value of attribute associated with the context namespace. You can use this function in both SQL and PL/SQL statements. The context namespace must already have been created, and the associated attribute and its value must also have been set using the DBMS_SESSION.SET_CONTEXT procedure. The namespace must be a valid SQL identifier, and the attribute name 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.)

Oracle8i provides a built-in namespace called USERENV, which describes the current session. The predefined attributes of namespace USERENV are listed Table 4-1, along with the lengths of their return strings.

See Also: Oracle8i 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. Oracle8i Supplied PL/SQL Packages Reference for information on the DBMS_SESSION.SET_CONTEXT procedure.

Example 1

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

SELECT SYS_CONTEXT ('USERENV', 'SESSION_USER') 
   FROM DUAL;

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

Example 2

The following 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;
 
User Group
----------
Sales

Table 4-1 Predefined Attributes of Namespace USERENV

Attribute	Return Value	Return Length (bytes)
TERMINAL	The operating system identifier for the client of the current session. In distributed SQL statements, this option returns the identifier for your local session. In a distributed environment, this is supported only for remote SELECTs, not for remote INSERTs, UPDATEs, or DELETEs. (The return length of this parameter may vary by operating system.)	10
LANGUAGE	The language and territory currently used by your session, along with the database character set, in this form: language_territory.characterset	52
LANG	The ISO abbreviation for the language name, a shorter form than the existing 'LANGUAGE' parameter.	62
SESSIONID	The auditing session identifier. You cannot use this option in distributed SQL statements.	30
INSTANCE	The instance identification number of the current instance.	30
ENTRYID	The available auditing entry identifier. You cannot use this option in distributed SQL statements. To use this keyword in USERENV, the initialization parameter AUDIT_TRAIL must be set to TRUE.	30
ISDBA	TRUE if you currently have the DBA role enabled and FALSE if you do not.	30
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
NLS_TERRITORY	The territory of the current session.	62
NLS_CURRENCY	The currency of the current session.	62
NLS_CALENDAR	The current calendar 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
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
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
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
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
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
HOST	Name of the host machine from which the client has connected.	54
OS_USER	Operating system username of the client process that initiated the database session	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
IP_ADDRESS	IP address of the machine from which the client is connected.	30
NETWORK_PROTOCOL	Network protocol being used for communication, as specified in the 'PROTOCOL=protocol' portion of the connect string.	256
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
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
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
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.