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What this article shares with you is about how to use the sys_context function correctly. The editor thinks it is very practical, so I share it with you to learn. I hope you can get something after reading this article.

The sys_context function is a predefined function provided by Oracle to obtain context information of the environment. This function returns a parameter value under the specified namespace. This function can be used in sql and PL/SQL languages. Sys_context is actually a container access function for Oracle to store and pass parameters. We log in to the Oracle server with session information and other attribute information. Some of them are predefined by Oracle and are automatically filled in to the specified variables when logging in to the system. The other function, userenv (), remains compatible with it.

Here is some information that can be obtained through the sys_context function:

Select sys_context ('USERENV',' TERMINAL') terminal

Sys_context ('USERENV',' LANGUAGE') language

Sys_context ('USERENV',' SESSIONID') sessionid

Sys_context ('USERENV',' INSTANCE') instance

Sys_context ('USERENV',' ENTRYID') entryid

Sys_context ('USERENV',' ISDBA') isdba

Sys_context ('USERENV',' NLS_TERRITORY') nls_territory

Sys_context ('USERENV',' NLS_CURRENCY') nls_currency

Sys_context ('USERENV',' NLS_CALENDAR') nls_calendar

Sys_context ('USERENV',' NLS_DATE_FORMAT') nls_date_format

Sys_context ('USERENV',' NLS_DATE_LANGUAGE') nls_date_language

Sys_context ('USERENV',' NLS_SORT') nls_sort

Sys_context ('USERENV',' CURRENT_USER') current_user

Sys_context ('USERENV',' CURRENT_USERID') current_userid

Sys_context ('USERENV',' SESSION_USER') session_user

Sys_context ('USERENV',' SESSION_USERID') session_userid

Sys_context ('USERENV',' PROXY_USER') proxy_user

Sys_context ('USERENV',' PROXY_USERID') proxy_userid

Sys_context ('USERENV',' DB_DOMAIN') db_domain

Sys_context ('USERENV',' DB_NAME') db_name

Sys_context ('USERENV',' HOST') host

Sys_context ('USERENV',' OS_USER') os_user

Sys_context ('USERENV',' EXTERNAL_NAME') external_name

Sys_context ('USERENV',' IP_ADDRESS') ip_address

Sys_context ('USERENV',' MODULE') module

Sys_context ('USERENV',' NETWORK_PROTOCOL') network_protocol

Sys_context ('USERENV',' BG_JOB_ID') bg_job_id

Sys_context ('USERENV',' FG_JOB_ID') fg_job_id

Sys_context ('USERENV',' AUTHENTICATION_TYPE') authentication_type

Sys_context ('USERENV',' AUTHENTICATION_DATA') authentication_data

Sys_context ('userenv',' SID') from dual

From dual

We can also define context parameters to pass values. Here is the format of the sys_context function:

Sys_context ('namespace',' parameter' {, length})

Where namespace is a group unit for storing information, and namespace is classified by category. There can be multiple parameter values under a namespace, which can be distinguished by different parameter. Namespace is a predefined SQL identifier, while parameter is an arbitrary case-insensitive string with a length of no more than 30 bits. The return value of the function is of type varchar2, and the length defaults to 256 bits. If you need to limit this default value, you can use the length parameter as the new return length value.

Set namespace to specify the parameter value, which can be done using the dbms_session.set_context method:

-- 1. Define namespace

Create context Test using set_test_context

-- 2. Definition method

Create or replace procedure set_test_context (vc_value in varchar2) is

Begin

Dbms_session.set_context ('Test', 'a1century, vc_value)

End

-- 3. Set value

Exec set_test_context ('m')

-- 4. Get the value

Select sys_context ('Test', 'a1') from dual

SYS_CONTEXT ('TEST','A1')

-

M

The above is how to correctly use the sys_context function, the editor believes that there are some knowledge points that we may see or use in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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