SET CONSTRAINT[S]

SET CONSTRAINT[S]

Purpose

Use the SET CONSTRAINTS statement to specify, for a particular transaction, whether a deferrable constraint is checked following each DML statement or when the transaction is committed.

Prerequisites

To specify when a deferrable constraint is checked, you must have SELECT privilege on the table to which the constraint is applied unless the table is in your schema.

Syntax

set_constraints::=

Semantics

constraint

Specify the name of one or more integrity constraints.

ALL

Specify ALL to set all deferrable constraints for this transaction.

IMMEDIATE

Specify IMMEDIATE to indicate that the conditions specified by the deferrable constraint are checked immediately after each DML statement.

DEFERRED

Specify DEFERRED to indicate that the conditions specified by the deferrable constraint are checked when the transaction is committed.

SQL Statements: SAVEPOINT to UPDATE 18-45

SET CONSTRAINT[S]

Note: You can verify the success of deferrable constraints prior to committing them by issuing a SET CONSTRAINTS ALL IMMEDIATE statement.

Examples

Setting Constraints: Examples The following statement sets all deferrable constraints in this transaction to be checked immediately following each DML statement:

SET CONSTRAINTS ALL IMMEDIATE;

The following statement checks three deferred constraints when the transaction is committed. This example fails if the constraints were specified to be NOT DEFERRABLE.

SET CONSTRAINTS emp_job_nn, emp_salary_min , hr.jhist_dept_fk@remote DEFERRED;

18-46 Oracle9i SQL Reference

SET ROLE

SET ROLE

Purpose

Use the SET ROLE statement to enable and disable roles for your current session.

When a user logs on, Oracle enables all privileges granted explicitly to the user and all privileges in the user’s default roles. During the session, the user or an application can use the SET ROLE statement any number of times to change the roles currently enabled for the session. The number of roles that can be concurrently enabled is limited by the initialization parameter MAX_ENABLED_ROLES.

You can see which roles are currently enabled by examining the SESSION_ROLES data dictionary view.

See Also:

■Oracle9i Database Reference for information on the SESSION_ ROLES session parameter

Prerequisites

You must already have been granted the roles that you name in the SET ROLE statement.

Syntax

set_role::=

ALL

NONE

SQL Statements: SAVEPOINT to UPDATE 18-47

SET ROLE

Semantics

role

Specify a role to be enabled for the current session. Any roles not listed and not already enabled are disabled for the current session.

In the IDENTIFIED BY password clause, specify the password for a role. If the role has a password, then you must specify the password to enable the role.

Restriction on Setting Roles You cannot specify a role unless it was granted to you either directly or through other roles.

ALL Clause

Specify ALL to enable all roles granted to you for the current session except those optionally listed in the EXCEPT clause.

Roles listed in the EXCEPT clause must be roles granted directly to you. They cannot be roles granted to you through other roles.

If you list a role in the EXCEPT clause that has been granted to you both directly and through another role, then the role remains enabled by virtue of the role to which it has been granted.

Restriction on the ALL Clause You cannot use this clause to enable roles with passwords that have been granted directly to you.

NONE

Specify NONE to disable all roles for the current session, including the DEFAULT role.

Examples

Setting Roles: Examples To enable the role dw_manager identified by the password warehouse for your current session, issue the following statement:

SET ROLE dw_manager IDENTIFIED BY warehouse;

To enable all roles granted to you for the current session, issue the following statement:

SET ROLE ALL;

18-48 Oracle9i SQL Reference

SET ROLE

To enable all roles granted to you except dw_manager, issue the following statement:

SET ROLE ALL EXCEPT dw_manager;

To disable all roles granted to you for the current session, issue the following statement:

SET ROLE NONE;

SQL Statements: SAVEPOINT to UPDATE 18-49