"not enforced" table constraints - sql, PL-SQL Programming

Assignment Help:

"Not Enforced" Table Constraints

A constraint that is not enforced is not really a constraint within the meaning of the act, but SQL does have such a concept and it needs to be mentioned here. With the exception of UNIQUE and PRIMARY KEY specifications, a table constraint can be declared as either ENFORCED (the default option) or NOT ENFORCED. The "enforcement characteristic" of such a constraint can be changed by means of an ALTER TABLE statement. For example, the table constraint MAX_ENROLMENTS becomes not enforced by execution of the statement ALTER TABLE ALTER CONSTRAINT MAX_ENROLMENTS NOT ENFORCED. The immediate effect is the same (ignoring effects on the catalog) as if ALTER TABLE DROP CONSTRAINT MAX_ENROLMENTS had been given. However, it's easier to reinstate the constraint using ALTER TABLE ALTER CONSTRAINT MAX_ENROLMENTS ENFORCED. NOT ENFORCED cannot be specified for domain constraints or assertions, so use of CREATE ASSERTION should really be the preferred method of declaring a constraint, but unfortunately that option is not widely available.


Related Discussions:- "not enforced" table constraints - sql

Anatomy of a table, Anatomy of a Table: Figure shows the terminology u...

Anatomy of a Table: Figure shows the terminology used in SQL to refer to parts of the structure of a table. As you can see, SQL has no official terms for its counterpa

How exceptions propagate in pl/sql programming?, How Exceptions Propagate ?...

How Exceptions Propagate ? Whenever an exception is raised, and if the PL/SQL cannot find a handler for it in the present subprogram or block, the exception propagates. That is

Block structure in pl/sql, Block Structure The PL/SQL is a block-struct...

Block Structure The PL/SQL is a block-structured language. That is, the fundamental units (procedures, anonymous blocks, and functions) that make up a PL/SQL program are logi

Miller-urey''s experimental procedure, MILLER-UREY' S EXPERIMENTAL PROCEDU...

MILLER-UREY' S EXPERIMENTAL PROCEDURES - They recreated the probable conditions on the primitive earth in the laboratory. An atmosphere containing hydrogen, ammonia, me

Begin parameter description in pl sql, BEGIN Parameter Description in pl sq...

BEGIN Parameter Description in pl sql: BEGIN: This keyword signals the beginning of the executable section of a PL/SQL block, that contains executable statements. The execut

Using raise_application_error - user-defined exceptions, Using raise_applic...

Using raise_application_error The Package DBMS_STANDARD that is supplied with Oracle gives language facilities that help your application to interact with Oracle. For illustra

Theory of eternity of life - origin of life, THEO R Y OF ETERNITY OF LIFE...

THEO R Y OF ETERNITY OF LIFE (PRAYER - 1880) - The theory of eternity of life, also called the steady-state theory , states that life has ever been in existence as at presen

Triggers, At times, customers make mistakes in submitting their orders and ...

At times, customers make mistakes in submitting their orders and call to cancel the order. Brewbean’s wants to create a trigger that automatically updates the stock level of all pr

How transactions guard your database, How Transactions Guard Your Database ...

How Transactions Guard Your Database The transaction is a sequence of SQL data manipulation statements which does a logical unit of work. The Oracle treats the sequence of SQL

Cursor attributes in pl sql, Cursor Attributes   The Cursors and curso...

Cursor Attributes   The Cursors and cursor variables have 4 attributes which give you helpful information about the execution of a data manipulation statement. Syntax:

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd