Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-01 |
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Purpose
Use the CREATE
CONTEXT
statement to:
Create a namespace for a context (a set of application-defined attributes that validates and secures an application) and
Associate the namespace with the externally created package that sets the context
You can use the DBMS_SESSION
.SET_CONTEXT
procedure in your designated package to set or reset the attributes of the context.
See Also:
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Prerequisites
To create a context namespace, you must have CREATE
ANY
CONTEXT
system privilege.
Syntax
create_context::=
Semantics
Specify OR
REPLACE
to redefine an existing context namespace using a different package.
namespace
Specify the name of the context namespace to create or modify. Context namespaces are always stored in the schema SYS
.
schema
Specify the schema owning package
. If you omit schema
, then Oracle Database uses the current schema.
package
Specify the PL/SQL package that sets or resets the context attributes under the namespace for a user session.
To provide some design flexibility, Oracle Database does not verify the existence of the schema or the validity of the package at the time you create the context.
The INITIALIZED
clause lets you specify an entity other than Oracle Database that can initialize the context namespace.
EXTERNALLY EXTERNALLY
indicates that the namespace can be initialized using an OCI interface when establishing a session.
See Also: Oracle Call Interface Programmer's Guide for information on using OCI to establish a session |
GLOBALLY GLOBALLY
indicates that the namespace can be initialized by the LDAP directory when a global user connects to the database.
After the session is established, only the designated PL/SQL package can issue commands to write to any attributes inside the namespace.
See Also:
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This clause indicates that any application context set in namespace
is accessible throughout the entire instance. This setting lets multiple sessions share application attributes.
Examples
Creating an Application Context: Example This example uses the PL/SQL package emp_mgmt
, created in "Creating a Package: Example", which validates and secures the hr
application. The following statement creates the context namespace hr_context
and associates it with the package emp_mgmt
:
CREATE CONTEXT hr_context USING emp_mgmt;
You can control data access based on this context using the SYS_CONTEXT
function. For example, suppose your emp_mgmt
package has defined an attribute new_empno
as a particular employee identifier. You can secure the base table employees
by creating a view that restricts access based on the value of new_empno
, as follows:
CREATE VIEW hr_org_secure_view AS SELECT * FROM employees WHERE employee_id = SYS_CONTEXT('hr_context', 'new_empno');