Have you ever tried to find out the database name or instance name without having access to data dictionary views?
How to get the client machine details from which you have connected to the Oracle database?
How can you find out the current session details?
How can you find out the current database schema you are using?
In Oracle PL/SQL we have a standard function SYS_CONTEXT which gives answers to all the above questions.
Purpose
The sys_context function can be used to retrieve information about the Oracle environment.
Syntax
The syntax for the sys_context function is:
SELECT sys_context('', '', );
FROM DUAL;
- 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.
Usage
Examples:
To findout current data base schema on which a program is running
SELECT sys_context('USERENV', 'CURRENT_SCHEMA') FROM DUAL;
To findout Instance name
SELECT sys_context('USERENV', 'INSTANCE_NAME') FROM DUAL;
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 |
Thanks to my friend Shashi Kiran Kunapuli for helping me in writing this post.