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
SYS_CONTEXT returns the value of parameter associated with the context namespace. You can use this function in both SQL and PL/SQL
statements.
For namespace and parameter, you can
specify either a string 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, which must be a NUMBER or a
value that can be implicitly converted to NUMBER. The
valid range of values is 1 to 4000 bytes. If you specify an invalid value, then
Oracle Database ignores it and uses the default.
Oracle
provides a built-in namespace called USERENV, which
describes the current session. The predefined parameters of namespace USERENV are listed in Table 5-11.
See Also:
- Oracle Database 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
- PL/SQL Packages and Types Reference for information on the DBMS_SESSION.set_context procedure
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;
|
Parameter
|
Return
Value
|
|
ACTION
|
Identifies
the position in the module (application name) and is set through the DBMS_APPLICATION_INFO package or OCI.
|
|
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.
|
|
AUTHENTICATED_IDENTITY
|
Returns
the identity used in authentication. In the list that follows, the type of
user is followed by the value returned:
|
|
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.
|
|
AUTHENTICATION_METHOD
|
Returns
the method of authentication. In the list that follows, the type of user is
followed by the method returned:
You can
use IDENTIFICATION_TYPE to distinguish between
external and enterprise users when the authentication method is Password,
Kerberos, or SSL.
|
|
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.
|
|
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.
|
|
CLIENT_INFO
|
Returns
up to 64 bytes of user session information that can be stored by an
application using the DBMS_APPLICATION_INFO package.
|
|
CURRENT_BIND
|
The
bind variables for fine-grained auditing.
|
|
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.
|
|
CURRENT_SCHEMAID
|
Identifier
of the default schema being used in the current session.
|
|
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.
|
|
CURRENT_SQL_LENGTH
|
The
length of the current SQL statement that triggers fine-grained audit or
row-level security (RLS) policy functions or event handlers. Valid only
inside the function or event handler.
|
|
DB_DOMAIN
|
Domain
of the database as specified in the DB_DOMAIN initialization parameter.
|
|
DB_NAME
|
Name of
the database as specified in the DB_NAME initialization parameter.
|
|
DB_UNIQUE_NAME
|
Name of
the database as specified in the DB_UNIQUE_NAME initialization parameter.
|
|
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. The correct auditing entry
identifier can be seen only through an audit handler for standard or
fine-grained audit.
|
|
ENTERPRISE_IDENTITY
|
Returns
the user's enterprise-wide identity:
The
value of the attribute differs by proxy method:
|
|
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.
|
|
GLOBAL_CONTEXT_MEMORY
|
Returns
the number being used in the System Global Area by the globally accessed
context.
|
|
GLOBAL_UID
|
Returns
the global user ID from Oracle Internet Directory for Enterprise User
Security (EUS) logins; returns null for all other logins.
|
|
HOST
|
Name of
the host machine from which the client has connected.
|
|
IDENTIFICATION_TYPE
|
Returns
the way the user's schema was created in the database. Specifically, it
reflects the IDENTIFIED clause in the CREATE/ALTER USER
syntax. In the list that follows, the syntax used during schema creation is
followed by the identification type returned:
|
|
INSTANCE
|
The
instance identification number of the current instance.
|
|
INSTANCE_NAME
|
The
name of the instance.
|
|
IP_ADDRESS
|
IP
address of the machine from which the client is connected.
|
|
ISDBA
|
Returns
TRUE if the user has been
authenticated as having DBA privileges either through the operating system or
through a password file.
|
|
LANG
|
The ISO
abbreviation for the language name, a shorter form than the existing 'LANGUAGE' parameter.
|
|
LANGUAGE
|
The
language and territory currently used by your session, along with the
database character set, in this form:
language_territory.characterset
|
|
MODULE
|
The
application name (module) set through the DBMS_APPLICATION_INFO package or OCI.
|
|
NETWORK_PROTOCOL
|
Network
protocol being used for communication, as specified in the 'PROTOCOL=protocol' portion of the connect string.
|
|
NLS_CALENDAR
|
The
current calendar of the current session.
|
|
NLS_CURRENCY
|
The
currency of the current session.
|
|
NLS_DATE_FORMAT
|
The
date format for the session.
|
|
NLS_DATE_LANGUAGE
|
The
language used for expressing dates.
|
|
NLS_SORT
|
BINARY or the linguistic sort basis.
|
|
NLS_TERRITORY
|
The
territory of the current session.
|
|
OS_USER
|
Operating
system user name of the client process that initiated the database session.
|
|
POLICY_INVOKER
|
The
invoker of row-level security (RLS) policy functions.
|
|
PROXY_ENTERPRISE_IDENTITY
|
Returns
the Oracle Internet Directory DN when the proxy user is an enterprise user.
|
|
PROXY_GLOBAL_UID
|
Returns
the global user ID from Oracle Internet Directory for Enterprise User
Security (EUS) proxy users; returns NULL for all other proxy users.
|
|
PROXY_USER
|
Name of
the database user who opened the current session on behalf of SESSION_USER.
|
|
PROXY_USERID
|
Identifier
of the database user who opened the current session on behalf of SESSION_USER.
|
|
SERVER_HOST
|
The
host name of the machine on which the instance is running.
|
|
SERVICE_NAME
|
The
name of the service to which a given session is connected.
|
|
SESSION_USER
|
For
enterprises users, returns the schema. For other users, returns the database
user name by which the current user is authenticated. This value remains the
same throughout the duration of the session.
|
|
SESSION_USERID
|
Identifier
of the database user name by which the current user is authenticated.
|
|
SESSIONID
|
The
auditing session identifier. You cannot use this attribute in distributed SQL
statements.
|
|
SID
|
The
session number (different from the session ID).
|
|
STATEMENTID
|
The
auditing statement identifier. STATEMENTID represents the number of SQL statements audited
in a given session. You cannot use this attribute in distributed SQL
statements. The correct auditing statement identifier can be seen only
through an audit handler for standard or fine-grained audit.
|
|
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.)
|
Table 5-12 lists the parameters of namespace USERENV that have been deprecated. Oracle suggests that
you use the alternatives suggested in the Comments column.
|
Parameter
|
Comments
|
|
AUTHENTICATION_TYPE
|
This
parameter returned a value indicating how the user was authenticated. The
same information is now available from the new AUTHENTICATION_METHOD parameter combined with IDENTIFICATION_TYPE.
|
|
CURRENT_USER
|
Use the
SESSION_USER parameter instead.
|
|
CURRENT_USERID
|
Use the
SESSION_USERID parameter instead.
|
|
EXTERNAL_NAME
|
This
parameter returned the external name of the user. More complete information
can now be obtained from the AUTHENTICATED_IDENTITY and ENTERPRISE_IDENTITY parameter.
|
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'
|
No comments:
Post a Comment