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Oracle9i SQL Reference
Release 2 (9.2)

Part Number A96540-02
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CREATE CONTEXT

Purpose

Use the CREATE CONTEXT statement to:

You can use the DBMS_SESSION.set_context procedure in your designated package to set or reset the attributes of the context.

See Also:

Prerequisites

To create a context namespace, you must have CREATE ANY CONTEXT system privilege.

Syntax

create_context::=

Text description of statements_5a.gif follows
Text description of create_context


Semantics

OR REPLACE

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, Oracle uses the current schema.

package

Specify the PL/SQL package that sets or resets the context attributes under the namespace for a user session.


Note:

To provide some design flexibility, Oracle does not verify the existence of the schema or the validity of the package at the time you create the context.


See Also:

Oracle9i Supplied PL/SQL Packages and Types Reference for more information on setting the package

INITIALIZED Clause

The INITIALIZED clause lets you specify an entity other than Oracle 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:

ACCESSED GLOBALLY

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');

See Also:

SYS_CONTEXT