Preamble
Oracle/PLSQL function SYS_CONTEXT is used to get information about the state of Oracle environment.
Syntax of Oracle/PLSQL function SYS_CONTEXT
SYS_CONTEXT( namespace_id, parameter_id, [ length_id ] )
- namespace_id – is an Oracle namespace that has already been created. If the ‘USERENV’ namespace is used, the description attributes of the current Oracle session can be returned.
- parameter_id – allowed attribute that was set using the DBMS_SESSION.SET_CONTEXT procedure.
- length_id – is optional. It’s the length of the return value in bytes. If this parameter is not specified or if an invalid input is specified, SYS_CONTEXT will be 256 bytes by default.
Note: The default value of SYS_CONTEXT is 256 bytes:
Allowed parameters for the ‘USERENV’ namespace: (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 |
The SYS_CONTEXT function can be used in the following versions of Oracle/PLSQL
Oracle 12c, Oracle 11g, Oracle 10g, Oracle 9i, Oracle 8i
Let’s consider some examples of Oracle SYS_CONTEXT function and learn how to use SYS_CONTEXT function in Oracle/PLSQL.
SELECT SYS_CONTEXT('USERENV', 'LANG') FROM DUAL;
--Result: RU
SELECT SYS_CONTEXT('USERENV', 'LANGUAGE') FROM DUAL;
--Result: RUSSIAN_CIS.CL8MSWIN1251.
SELECT SYS_CONTEXT('USERENV', 'NLS_CALENDAR') FROM DUAL;
--Result: GREGORIAN
SELECT SYS_CONTEXT('USERENV', 'NLS_DATE_FORMAT') FROM DUAL;
--Result: DD.MM.RR
SELECT SYS_CONTEXT('USERENV', 'NLS_TERRITORY') FROM DUAL;
--Result: CIS
SQL Tutorial For Beginners : What is SYS_CONTEXT in Oracle with Example
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