Oracle SYS_CONTEXT Function with Examples (including Oracle 12C)
The SYS_CONTEXT function is an Oracle function that checks configuration values on the database. Learn how to use it and see some examples in this article.
Purpose of the Oracle SYS_CONTEXT Function
The purpose of the Oracle SYS_CONTEXT function is to return information about the Oracle environment that you're working on.
Syntax
The syntax of the SYS_CONTEXT function is:
1SYS_CONTEXT ('namespace', 'parameter' [, length] )
Parameters
The parameters of the SYS_CONTEXT function are:
- namespace (mandatory): This is an Oracle namespace that has been created. A common namespace to use for this function is "USERENV". It must be within quotes.
- parameter (mandatory): A valid parameter attribute that the value is to be returned for. It can be set using the dbms_session.set_context procedure.
- length (optional): The length of the return value, in bytes. The default value is 256 if this value is not specified.
Some other notes about this function:
- For the namespace and parameter, you can specify a string or an expression that resolves to a string (e.g. selecting from a table of namespaces)
- The parameter is not case-sensitive and must be less than or equal to 30 characters.
- The return type is VARCHAR2.
- The length value must be a NUMBER or a value that can be converted to a number.
- The length value can be between 1 and 4000. If the value is invalid, Oracle ignores it and uses the default value (256).
- The USERENV namespace describes the current session.
Can You List All of the Parameters Used in SYS_CONTEXT?
If by "listing all parameters" you mean "show a list of the parameters I can use in the Oracle SYS_CONTEXT function", then yes. Refer to the table below for the possible inputs into this function.
What Are the Oracle SYS_CONTEXT Parameters for Oracle 12C?
You can find them in the table below, where I've included the parameters for the last 4 major Oracle versions.
Parameters of SYS_CONTEXT for USERENV Namespace
This table lists all of the parameter values that can be used within the USERENV namespace. This can give you a lot of information about the user session.
| Parameter | Explanation | Oracle 9i | Oracle 10g | Oracle 11g | Oracle 12c |
|---|---|---|---|---|---|
| ACTION | Identifies the position in the module (application name) | No | Yes | Yes | Yes |
| AUDITED_CURSORID | Returns the cursor ID of the SQL that triggered the audit | Yes | Yes | Yes | Yes |
| AUTHENTICATED_IDENTITY | Returns the identity used in authentication | No | Yes | Yes | Yes |
| AUTHENTICATION_DATA | Data being used to authenticate the login user | Yes | Yes | Yes | Yes |
| AUTHENTICATION_METHOD | Returns the method of authentication | No | Yes | 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 | 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 | Yes |
| CDB_NAME | If queried while connected to a multitenant container database (CDB), returns the name of the CDB. Otherwise, returns null. | No | No | No | Yes |
| CLIENT_IDENTIFIER Returns the client identifier, which is used to identify users that authenticate as the same database user | Yes | Yes | Yes | Yes | |
| CLIENT_INFO | Returns up to 64 bytes of user session information | Yes | Yes | Yes | Yes |
| CLIENT_PROGRAM_NAME | The name of the program used for the database session. | No | No | No | Yes |
| CON_ID | If queried while connected to a CDB, returns the current container ID. Otherwise, returns 0. | No | No | No | Yes |
| CON_NAME | If queried while connected to a CDB, returns the current container name. Otherwise, returns the name of the database as specified in the DB_NAME initialization parameter. | No | No | No | Yes |
| CURRENT_BIND | The bind variables for fine-grained auditing | No | Yes | Yes | Yes |
| CURRENT_EDITION_ID | The identifier of the current edition. | No | No | No | Yes |
| CURRENT_EDITION_NAME | The name of the current edition. | No | No | No | Yes |
| CURRENT_SCHEMA | Returns the name of the currently active default schema | Yes | Yes | Yes | Yes |
| CURRENT_SCHEMAID | Identifier of the currently active default schema. | Yes | Yes | Yes | Yes |
| CURRENT_SQL | Returns the first 4k bytes of the SQL that triggered the audit event | Yes | Yes | Yes | Yes |
| CURRENT_SQLn | Returns the n number of 4k bytes of the SQL that triggered the audit event, where n is a number from 1 to 7. For example, CURRENT_SQL1 returns bytes from 4k to 8k, CURRENT_SQL2 returns bytes from 8k to 12k. | Yes | Yes | Yes | Yes |
| CURRENT_SQL_LENGTH | Returns the length of the current SQL statement that triggered the audit event | No | Yes | Yes | Yes |
| CURRENT_USER | Name of the current user | Yes | No | No | No |
| CURRENT_USERID | Userid of the current user | Yes | No | No | No |
| 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. | No | No | No | Yes |
| DB_DOMAIN | Domain of the database from the DB_DOMAIN initialization parameter | Yes | Yes | Yes | Yes |
| DB_NAME | Name of the database from the DB_NAME initialization parameter | Yes | Yes | Yes | Yes |
| DB_SUPPLEMENTAL_LOG_LEVEL | If supplemental logging is enabled, returns a string containing the list of enabled supplemental logging levels. Possible values are: ALL_COLUMN, FOREIGN_KEY, MINIMAL, PRIMARY_KEY, PROCEDURAL, and UNIQUE_INDEX. If supplemental logging is not enabled, returns null. | No | No | No | Yes |
| DB_UNIQUE_NAME | Name of the database from the DB_UNIQUE_NAME initialization parameter | No | Yes | Yes | Yes |
| DBLINK_INFO | Returns the source of a database link session. Returns a string of "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 | No | No | No | Yes |
| ENTRYID | Available auditing entry identifier | Yes | Yes | Yes | Yes |
| ENTERPRISE_IDENTITY | Returns the user's enterprise-wide identity | No | Yes | Yes | Yes |
| EXTERNAL_NAME | External of the database user | Yes | No | No | No |
| FG_JOB_ID | If queried from within a job that was created using the DBMS_JOB package: If the session was established by a client foreground process, this parameter will return the Job ID. Otherwise, it will return NULL. Otherwise, it returns 0 | Yes | Yes | Yes | Yes |
| GLOBAL_CONTEXT_MEMORY | The number used in the System Global Area by the globally accessed context | Yes | 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 | Yes |
| HOST | Name of the host machine from which the client has connected | Yes | Yes | Yes | Yes |
| IDENTIFICATION_TYPE | Returns the way the user's schema was created. Specifically, it reflects the IDENTIFIED clause in the CREATE/ALTER USER syntax | No | Yes | Yes | Yes |
| INSTANCE | The identifier number of the current instance | Yes | Yes | Yes | Yes |
| INSTANCE_NAME | The name of the current instance | No | Yes | Yes | Yes |
| IS_APPLY_SERVER | Returns TRUE if queried from within a SQL Apply server in a logical standby database. Otherwise, returns FALSE. | No | No | No | Yes |
| IS_DG_ROLLING_UPGRADE | Returns TRUE if a rolling upgrade of the database software in a Data Guard configuration, initiated by way of the DBMS_ROLLING package, is active. Otherwise, returns FALSE. | No | No | No | Yes |
| IP_ADDRESS | IP address of the machine from which the client has connected. If the client and server are on the same machine and the connection uses IPv6 addressing, then ::1 is returned. | Yes | Yes | Yes | Yes |
| ISDBA | Returns TRUE if the user has DBA privileges. Otherwise, it will return FALSE. | Yes | Yes | Yes | Yes |
| LANG | The ISO abbreviation for the language (a shorter form than the existing 'LANGUAGE' parameter) | Yes | Yes | Yes | Yes |
| LANGUAGE | The language, territory, and character of the session. In the following format: language_territory.characterset | Yes | Yes | Yes | Yes |
| MODULE | Returns the application name set through DBMS_APPLICATION_INFO package or OCI | No | Yes | Yes | Yes |
| NETWORK_PROTOCOL | Network protocol being used for communication, as specified in the 'PROTOCOL=protocol' portion of the connect string. | Yes | Yes | Yes | Yes |
| NLS_CALENDAR | The calendar of the current session | Yes | Yes | Yes | Yes |
| NLS_CURRENCY | The currency of the current session | Yes | Yes | Yes | Yes |
| NLS_DATE_FORMAT | The date format for the current session | Yes | Yes | Yes | Yes |
| NLS_DATE_LANGUAGE | The language used for dates | Yes | Yes | Yes | Yes |
| NLS_SORT | BINARY or the linguistic sort basis | Yes | Yes | Yes | Yes |
| NLS_TERRITORY | The territory of the current session | Yes | Yes | Yes | Yes |
| ORACLE_HOME | The full path name for the Oracle home directory. | No | No | No | Yes |
| OS_USER | The OS username for the user logged in | Yes | Yes | Yes | Yes |
| PLATFORM_SLASH | The slash character that is used as the file path delimiter for your platform. | No | No | No | Yes |
| POLICY_INVOKER | The invoker of row-level security policy functions | No | Yes | Yes | Yes |
| PROXY_ENTERPRISE_IDENTITY | The Oracle Internet Directory DN when the proxy user is an enterprise user | No | Yes | 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 | Yes |
| PROXY_USER | The name of the user who opened the current session on behalf of SESSION_USER | Yes | Yes | Yes | Yes |
| PROXY_USERID | The identifier of the user who opened the current session on behalf of SESSION_USER | Yes | Yes | Yes | Yes |
| SCHEDULER_JOB | Returns Y if the current session belongs to a foreground job or background job. Otherwise, returns N. | No | No | No | Yes |
| SERVER_HOST | The host name of the machine where the instance is running | No | Yes | Yes | Yes |
| SERVICE_NAME | The name of the service that the session is connected to | No | Yes | Yes | Yes |
| SESSION_EDITION_ID | The identifier of the session edition. | No | No | No | Yes |
| SESSION_EDITION_NAME | The name of the session edition. | No | No | No | Yes |
| SESSION_USER | The database user name of the user logged in | Yes | Yes | Yes | Yes |
| SESSION_USERID | The database identifier of the user logged in | Yes | Yes | Yes | Yes |
| SESSIONID | The identifier of the auditing session | Yes | Yes | Yes | Yes |
| SID | Session number | No | Yes | Yes | Yes |
| STATEMENTID | The auditing statement identifier | No | Yes | Yes | Yes |
| TERMINAL | The OS identifier of the current session | Yes | Yes | Yes | Yes |
| UNIFIED_AUDIT_SESSIONID | If queried while connected to a database that uses unified auditing or mixed mode auditing, returns the unified audit session ID. If queried while connected to a database that uses traditional auditing, returns null. | No | No | No | Yes |
What About the Oracle USER Function?
There’s a similar function in Oracle called USER.
The Oracle USER function provides you with the user ID of the current Oracle session.
It’s a simple function that takes no parameters.
The syntax of the USER function is:
1USER
That’s it. No parameters or anything. It can work just like a keyword.
The differences between USER and SYS_CONTEXT are:
- USER – Returns the name of the session user (the user who logged on). The same as SESSION_USER below.
- SYS_CONTEXT(‘USERENV’, ‘CURRENT_USER) – The name of the database user whose privileges are currently active. This may change during the session.
- SYS_CONTEXT(‘USERENV’, ‘SESSION_USER) – The name of the database user at logon. Does not change throughout the session.
What About the Oracle USERENV Function?
The purpose of the USERENV function is to get information about your current session. It’s a simple function but can take a few different values for its parameter.
However, it is a deprecated function.
USERENV is a deprecated function that is retained for compatibility with older versions. Oracle recommends that the SYS_CONTEXT function be used instead.
If you want to stop using USERENV and start using SYS_CONTEXT, you can call the SYS_CONTEXT function, with the first parameter of USERENV and the second parameter equal to the values in the above table.
For example, this function:
1USERENV('CLIENT_INFO')
Can be replaced with:
1SYS_CONTEXT('USER_ENV', 'CLIENT_INFO')
Examples of the Oracle SYS_CONTEXT Function
Here are some examples of the Oracle SYS_CONTEXT function. I find that examples are the best way for me to learn about code, even with the explanation above.
Example 1 - NLS_DATE_LANGUAGE
This example shows what the NLS_DATE_LANGUAGE is on the database.
1SELECT sys_context('USERENV', 'NLS_DATE_LANGUAGE');
Result:
1ENGLISH
Example 2 - NLS_DATE_FORMAT
This example shows what the date format is on the database.
1SELECT sys_context('USERENV', 'NLS_DATE_FORMAT');
Result:
1DD/MON/RR
Example 3 - CURRENT_SCHEMA
This example shows what the current schema is.
1SELECT sys_context('USERENV', 'CURRENT_SCHEMA');
Result:
1PETER
You can find a full list of Oracle SQL functions here.
Lastly, if you enjoy the information and career advice I've been providing, sign up to my newsletter below to stay up-to-date on my articles. You'll also receive a fantastic bonus. Thanks!
comments powered by Disqus