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 The Oracle PL/SQL SYS_CONTEXT Command      [Return To Index] Jump to:  
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Term: SYS_CONTEXT

Definition:
In Oracle PL/SQL, SYS_CONTEXT is used to get relevant information about the Oracle database environment. It accepts three parameters:, NAMESPACE, PARAMETER and LENGTH. Oracle's built in Namespace 'USERENV' is an SQL identifier, used to retrieve current session information. Parameters are the information variables which are associated to the Namespace and which have been set using the DBMS_SESSION.SET_CONTEXT procedure.
It returns character-based output whose length can be set by the LENGTH parameter. The valid range for the LENGTH parameter is from 1 to 4000.

The list below shows latest USERENV namespace parameters available in Oracle 11g which provide current session information in the database:

Parameter Return Value Return Length (bytes)
ACTION Identifies the position in the module (application name) and is set through the DBMS_APPLICATION_INFO package or OCI. 32
AUDITED_CURSORID Returns the cursor ID of the SQL that triggered the audit. This parameter is not valid in a fine-grained auditing environment. If you specify it in such an environment, Oracle Database always returns NULL. 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.

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 Database implements such a change.

256
AUTHENTICATION_TYPE How the user was authenticated:
  • DATABASE: user name/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 Database background process. Null if the session was not established by a background process. 64
CLIENT_IDENTIFIER Returns an identifier that is set by the application through the DBMS_SESSION.SET_IDENTIFIER procedure, the OCI attribute OCI_ATTR_CLIENT_IDENTIFIER, or the Java class Oracle.jdbc.OracleConnection.setClientIdentifier. This attribute is used by various database components to identify lightweight application users who authenticate as the same database user. 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

CURRENT_SQLn

CURRENT_SQL returns the first 4K bytes of the current SQL that triggered the fine-grained auditing event. The CURRENT_SQLn attributes return subsequent 4K-byte increments, where n can be an integer from 1 to 7, inclusive. CURRENT_SQL1 returns bytes 4K to 8K; CURRENT_SQL2 returns bytes 8K to 12K, and so forth. You can specify these attributes only inside the event handler for the fine-grained auditing feature. 4
CURRENT_USER This attribute is being deprecated. Use the SESSION_USER attribute instead. 30
CURRENT_USERID This attribute is being deprecated. Use the SESSION_USERID attribute instead. 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
DB_UNIQUE_NAME Name of the database as specified in the DB_UNIQUE_NAME initialization parameter. 30
ENTRYID The current audit entry number. The audit entryid sequence is shared between fine-grained audit records and regular audit records. You cannot use this attribute in distributed SQL statements. 30
EXTERNAL_NAME External name of the database user. For SSL authenticated sessions using v.503 certificates, this parameter 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
MODULE The application name (module) set through the DBMS_APPLICATION_INFO package or OCI. 48
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 user name 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
SERVICE_NAME The name of the service to which a given session is connected. 64
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
STATEMENTID The auditing statement identifier. STATEMENTID represents the number of SQL statements audited in a given session. NA
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


Example Syntax:

SYS_CONTEXT ( ' namespace ' , ' parameter ', length)


Example Usage:

The SQL queries below display the parameter values for CURRENT_SCHEMA, DB_NAME and LANGUAGE in the USERENV namespace.

SQL> SELECT SYS_CONTEXT('USERENV', 'CURRENT_SCHEMA') FROM dual;

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

SQL> SELECT SYS_CONTEXT('USERENV', 'DB_NAME') FROM dual;

SYS_CONTEXT('USERENV','DB_NAME')
----------------------------------------
SYSTEM

SQL> SELECT SYS_CONTEXT('USERENV', 'LANGUAGE') FROM dual;

SYS_CONTEXT('USERENV','LANGUAGE')
--------------------------------------
AMERICAN_AMERICA.WE8MSWIN1252



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