how to get session information
有时候我们需要知道当前连接会话的session信息，有多种办法的到当前session的相关信息。
1 V$MYSTAT
通过这个视图可以得到基本的信息，通常我通过该视图得到SID
SQL> select sid from v$mystat where rownum=1;
SID
----------
1564
2 Userenv
这个是强大的内置函数，通过该函数可以得到登陆用户的相关信息，比如要从v$session获得信息：
SQL> SELECT Sid,serial#,audsid,username From v$session Where Sid=Userenv('SID');
SID SERIAL# AUDSID USERNAME
---------- ---------- ---------- ------------------------------
1564 65273 4294967295 SYS
与Userenv类似功能的还有SYS_CONTEXT函数，后者比前者提够的更为强大的功能，oracle强烈建议用有SYS_CONTEXT替代Userenv使用。
3 SYS_CONTEXT
SQL> SELECT Sid,serial#,audsid,username From v$session Where Sid=SYS_CONTEXT('USERENV','SID');
SID SERIAL# AUDSID USERNAME
---------- ---------- ---------- ------------------------------
1564 65273 4294967295 SYS
4 参考如下资料：
4.1 USERENV
语法
Userenv('parameter')
提示
USERENV是个历史遗留功能，保留它只是为了向后兼容。oracle建议你是用SYS_CONTEXT函数功能来替代USERENV功能。
USERENV返回当前session的相关信息。这些信息可以被用来编写特定程序审计或者决定和修改当前连接session的字符集。不能使用USERENV来定义check约束。
所有调用USERENV函数返回的结果是VARCHAR2数据，除了这些输入参数：SESSIONID,SID,ENTRYID返回的是NUMBER数据。
USERENV的parameters
CLIENT_INFO 返回64字节用户session信息，可以在应用程序中被DBMS_APPLICATION_INFO调用。
ENTRYID 当前审计条目数。注意，无法在分布式SQL语句中使用。
ISDBA 返回TRUE或者FALSE，当通过操作系统使用DBA权限或者口令文件登陆，返回的是TRUE。
LANG 返回数据库语言的ISO缩写，如ZHS
LANGUAGE 返回当前session的操作系统终端的NLS_LANG：language_territory.characterset。
SESSIONID 返回审计会话标识。注意，无法在分布式SQL语句中使用。
TERMINAL 返回操作系统终端。在分布式SQL语句中，这个参数返回你本地的终端信息。在分布式环境中，这个参数仅仅在远程SELECT语句中被支持，无法在远程INSERT,U PDATE或者DELETE操作中使用。
示例
SQL> !cat .bash_profile
export NLS_LANG=AMERICAN_AMERICA.zhs16gbk
SQL> begin
2 DBMS_APPLICATION_INFO.set_client_info('is test for client info');
3 end;
4 /
PL/SQL procedure successfully completed.
SQL> Select Userenv('CLIENT_INFO'),
2 Userenv('ENTRYID'),
3 Userenv('ISDBA'),
4 Userenv('LANG'),
5 Userenv('LANGUAGE'),
6 Userenv('SESSIONID'),
7 Userenv('Sid'),
8 Userenv('TERMINAL')
9 From Dual;
USERENV('CLIENT_INFO')
----------------------------------------------------------------
USERENV('ENTRYID') USEREN USERENV('LANG')
------------------ ------ ----------------------------------------------------
USERENV('LANGUAGE') USERENV('SESSIONID')
---------------------------------------------------- --------------------
USERENV('SID') USERENV('TERMINAL')
-------------- ------------------------------
is test for client info
0 TRUE US
AMERICAN_AMERICA.ZHS16GBK 4294967295
1564 pts/5
SQL>
4.2 SYS_CONTEXT
语法
SYS_CONTEXT('namespace', 'parameter' [, length ])
提示
可以在SQL和PL/SQL语句中使用。对应前面2个参数命名空间和参数，可以指定为字符串或者可以被解析为字符串的表达式。命名空间必须已经存在，或者可以使用DBMS_SESSION.set_context来创建你自己的属性环境。
使用dbms_session.set_context设置环境属性：
SQL> create or replace procedure p_set_mycontext(p_attr varchar2,p_value varchar2)
2 is
3 begin
4 dbms_session.set_context('mycontext',p_attr,p_value);
5 end;
6 /
Procedure created
SQL> create or replace context mycontext using p_set_mycontext;
Context created
SQL> exec p_set_mycontext('name','nyfor');
PL/SQL procedure successfully completed
SQL> select sys_context('mycontext','name') from dual;
SYS_CONTEXT('MYCONTEXT','NAME'
--------------------------------------------------------------------------------
nyfor
函数返回值是VARCHAR2。默认返回值长度是256字节，你可以通过length参数设定返回长度。
这个函数的参数太多了，自己参考吧：
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, then 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:
Kerberos-authenticated enterprise user: kerberos principal name
Kerberos-authenticated external user : kerberos principal name; same as the schema name
SSL-authenticated enterprise user: the DN in the user's PKI certificate
SSL-authenticated external user: the DN in the user's PKI certificate
Password-authenticated enterprise user: nickname; same as the login name
Password-authenticated database user: the database username; same as the schema name
OS-authenticated external user: the external operating system user name
Radius-authenticated external user: the schema name
Proxy with DN : Oracle Internet Directory DN of the client
Proxy with certificate: certificate DN of the client
Proxy with username: database user name if client is a local database user; nickname if client is an enterprise user.
SYSDBA/SYSOPER using Password File: login name
SYSDBA/SYSOPER using OS authentication: operating system user name
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:
Password-authenticated enterprise user, local database user, or SYSDBA/SYSOPER using Password File; proxy with username using password: PASSWORD
Kerberos-authenticated enterprise or external user: KERBEROS
SSL-authenticated enterprise or external user: SSL
Radius-authenticated external user: RADIUS
OS-authenticated external user or SYSDBA/SYSOPER: OS
Proxy with certificate, DN, or username without using password: NONE
Background process (job queue slave process): JOB
Parallel Query Slave process: PQ_SLAVE
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.setEndToEndMetrics. 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. You can specify this attribute only inside the event handler for the fine-grained auditing feature.
CURRENT_EDITION_ID
The identifier of the current edition.
CURRENT_EDITION_NAME
The name of the current edition.
CURRENT_SCHEMA
The name of the currently active default schema. This value may change during the duration of a session through use of an ALTER SESSION SET CURRENT_SCHEMA statement. This may also change during the duration of a session to reflect the owner of any active definer's
rights object. When used directly in the body of a view definition, this returns the default schema used when executing the cursor that is using the view; it does not respect views used in the cursor as being definer's rights.
Note: Oracle recommends against issuing the SQL statement ALTER SESSION SET CURRENT_SCHEMA from within a stored PL/SQL unit.
CURRENT_SCHEMAID
Identifier of the currently active default schema.
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. You can specify this attribute only inside the event handler for the fine-grained auditing feature.
CURRENT_USER
The name of the database user whose privileges are currently active. This may change during the duration of a session to reflect the owner of any active definer's rights object. When no definer's rights object is active, CURRENT_USER returns the same value
as SESSION_USER. When used directly in the body of a view definition, this returns the user that is executing the cursor that is using the view; it does not respect views used in the cursor as being definer's rights.
CURRENT_USERID
The identifier of the database user whose privileges are currently active.
DATABASE_ROLE
The database role using the SYS_CONTEXT function with the USERENV namespace. The role is one of the following: PRIMARY, PHYSICAL STANDBY, LOGICAL STANDBY, SNAPSHOT STANDBY.
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.
DBLINK_INFO
Returns the source of a database link session. Specifically, it returns a string of the form:
SOURCE_GLOBAL_NAME=dblink_src_global_name, DBLINK_NAME=dblink_name, SOURCE_AUDIT_SESSIONID=dblink_src_audit_sessionid
where:
dblink_src_global_name is the unique global name of the source database
dblink_name is the name of the database link on the source database
dblink_src_audit_sessionid is the audit session ID of the session on the source database that initiated the connection to the remote database using dblink_name
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:
For enterprise users: the Oracle Internet Directory DN.
For external users: the external identity (Kerberos principal name, Radius schema names, OS user name, Certificate DN).
For local users and SYSDBA/SYSOPER logins: NULL.
The value of the attribute differs by proxy method:
For a proxy with DN: the Oracle Internet Directory DN of the client
For a proxy with certificate: the certificate DN of the client for external users; the Oracle Internet Directory DN for global users
For a proxy with username: the Oracle Internet Directory DN if the client is an enterprise users; NULL if the client is a local database user.
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:
IDENTIFIED BY password: LOCAL
IDENTIFIED EXTERNALLY: EXTERNAL
IDENTIFIED GLOBALLY: GLOBAL SHARED
IDENTIFIED GLOBALLY AS DN: GLOBAL PRIVATE
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. If the client and server are on the same machine and the connection uses IPv6 addressing, then ::1 is returned.
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 abbreviated name for the language, 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_EDITION_ID
The identifier of the session edition.
SESSION_EDITION_NAME
The name of the session edition.
SESSION_USER
The name of the database user at logon. For enterprise users, returns the schema. For other users, returns the database user name. This value remains the same throughout the duration of the session.
SESSION_USERID
The identifier of the database user at logon.
SESSIONID
The auditing session identifier. You cannot use this attribute in distributed SQL statements.
SID
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.)
示例
store@TEST> Select Sys_Context('USERENV', 'ACTION'),
Sys_Context('USERENV', 'SESSIONID'),
Sys_Context('USERENV', 'SID'),
Sys_Context('USERENV', 'TERMINAL'),
Sys_Context('USERENV', 'HOST')
From Dual;
Sys_Context('USERENV', 'SERVER_HOST'),
Sys_Context('USERENV', 'SESSION_USER'),
Sys_Context('USERENV', 'SESSIONID'),
Sys_Context('USERENV', 'SID'),
Sys_Context('USERENV', 'TERMINAL'),
Sys_Context('USERENV', 'HOST')
8 From Dual;
SYS_CONTEXT('USERENV','ACTION')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','SERVER_HOST')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','SESSION_USER')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','SESSIONID')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','SID')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','TERMINAL')
----------------------------------------------------------------------------------------------------
SYS_CONTEXT('USERENV','HOST')
----------------------------------------------------------------------------------------------------
gtlions
STORE
520283
87
pts/2
gtlions
5 小结
关键词：V$MYSTAT，USERENV,SYS_CONTEXT，DBMS_APPLICATION_INFO,DBMS_SESSION
-The End-