advantages, disadvantages & codd rule compliance

8/10/2019 Advantages, Disadvantages & Codd Rule Compliance

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NAME REG NO

BELLARMINE LWANGA COM/0009/10

TRIUMPH MWONGELI SIT/0040/10DOUGLAS SHIKUTWA SIT/0540/11

EDIMUND KIGIO COM/0031/10

IGNATIUS OJIAMBO COM/0510/10

CECIL JUMBA A COM/0542/10


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Codd rule is a set of 13 rules number 0-12 proposed by

Edgar F. Codd. A

OracleTM

database referred to OracleTM

RDBMS or simplyas objectrelational database management systems

produced and marketed by OracleTMCorporation.


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The system must qualify as relational, as a database, and

as a management system. For a system to qualify as a

relational database management system (RDBMS), that

system must use its relational facilities (exclusively) to

manage the database. With adherence to the other rules,

oracle adheres to this rule.


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All data should be presented to the user in tabular formImplementation of Oracle.

All information in an Oracle database including table names,

column names are represented by values in tables.

Oracle satisfies complies fully with this rule by storing allvalues in a table. This simple view of data speeds design and

learning. User productivity is improved since knowledge of

only one language is necessary to access all data such as

description of the table and attribute definitions, integrityconstraints. Action can be taken when the constraints are

violated. Access to data can be restricted. All these

information are also stored in tables.


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Each item of data should be accessible without ambiguity.

In a purely relational database such as oracle this is

accomplished through a combination of the table name,

primary key and column name. This rule cannot be met

unless every table both has a primary key and the

uniqueness of that key is rigorously enforced. Pointers

were a key feature of earlier database management

software and most master or detail navigation relied on

them. In the relational model pointers simply do not

meet the guaranteed access rule and are not part of the

scheme


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A field should be allowed to remain empty. This involves

the support of a Nullvalue, which is distinct from an

empty string or a number with a value of zero. Of course,

this can't apply to primary keys. In addition, most

database implementations support the concept of a nun-

null field constraint that prevents null values in a specific

table column. Nullvalues must be uniformly treated as

"missing information," not as empty strings, blanks, or

zeros.
http://www.orafaq.com/wiki/NULLhttp://www.orafaq.com/wiki/NULLhttp://www.orafaq.com/wiki/NULLhttp://www.orafaq.com/wiki/NULL


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Oracle provides support for this rule as of null value byhandling records that have unknown or inapplicable

values in a pre-defined fashion. Also by distinguishing

between zeros, blanks and nulls in the records hand

handles such values in a consistent manner that producescorrect answers, comparisons and calculations. Through

the set of rules for handling nulls, users can distinguish

results of the queries that involve nulls, zeros and blanks.

Even though the rule doesnt specify what should bedone in the case of nulls it specifies that there should be a

consistent policy in the treatment of nulls.


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A relational database must provide access to its structure

through the same tools that are used to access the data.

(This is usually accomplished by storing the structure

definition within special system tables.)

Oracle satisfies this rule.

Has "hidden" tables that provides some access to the

data structure


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Database must support at least one clearly definedlanguage that includes functionality for data definitionand manipulation.

This rule is supported in oracle

All commercial relational databases use forms of thestandard SQL (Structured Query Language) as theirsupported comprehensive language.

Oracle uses SQL to change data definition, datamanipulation, data integrity and database transactioncontrol.


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Here each rule should support the same full range of data

manipulation whose direct access to a table is available

Oracle does not support this. They do provide somelimited view-updating for simple views. Oracle provides

the facility to programmatically allow view updating via

"instead-of" triggers.

In practice, providing update and delete access to logicalviews is difficult and is not fully supported by any current

database.


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A single operation must be able to retrieve, insert, update, or deletedata.

Data can be retrieved from a relational database in sets constructedof data from multiple rows and/or multiple tables. This rule statesthat insert, update, and delete operations should be supported for

any retrievable set rather than just for a single row in a single table.

High-level Insert, Update, and Delete: Data can be retrieved from arelational database in sets constructed of data from multiple rowsand/or multiple tables. (This rule states that insert, update, and

delete operations should be supported for any retrievable set ratherthan just for a single row in a single table.)

It does provide some limited view-updating for simple views. Oracleprovides the facility to programmatically allow view updating via"instead-of" triggers.

Oracle does not support this role because its termed difficult


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It states that the user(the person coding the sql

statements) is isolated from the physical method of

storage and retrieval of information from a database.

This rule is supported in oracle. For query and update

operations oracle completely meets this requirement,

allowing sql to be written with no knowlegde whatever of

the underlying software or hardware. One of the great

strengths of oracle over the years has been the ease with

which an application can be moved from one server

technology to another without any change whatever.


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States that the viewing of data by a user should not

change when the table structure of database changes

This rule is not supported in oracle because oracle relieson strong ties between the user view of the data and the

actual structure of the underlying tables


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The database language (like Oracle) should supportconstraints on user input that maintain database .

-the following is how Oracle follows the Integrityindependence rule

i Proxy Authentication in Oracle8i.

The OCI proxy authentication feature was initiallyreleased in Oracle8i.

It enabled a database client to set up, within a single

database connection, a number of "lightweight" usersessions, each of which is associated with a differentdatabase user.


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ii. Proxy Authentication in Oracle9i.

In Oracle9iproxy authentication, authentication of theclient is supported in the following ways:

Through a database password that is given when the useaccesses Oracle9iproxy authentication

Through a distinguished name or X.509 certificate

In Oracle9ithis feature is designed so that a specific middletier can be restricted to acting on behalf of a specified set ofusers.

Once the middle tier has authenticated itself to thedatabase, it can establish a lightweight session on behalf ofthose users without submitting user-specific authenticationinformation such as passwords.


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Authentication and Access Controls in Oracle9i

Oracle9iprovides user authentication to ensure that the

identity of a user, host or client is correctly known. To

access a database, a user must supply a valid username and

associated password of the database. These prevent

unauthorized use. Oracle9ialso provides authorization, to

ensure that a user, program, or process receives the

appropriate privileges to access an object or set of objects

To prevent unauthorized use of a database username,

Oracle provides user validation by several different

methods for normal database users. You can perform

authentication by:

The operating system

The associated Oracle database


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Further, Oracle Enterprise Edition supports

additional modes of authentication: The Oracle database of a middle-tier application

that performs transactions on behalf of the user.

The Secure Socket Layer (SSL) protocol.

A network service (through Oracle AdvancedSecurity).

For simplicity, one method is usually used to

authenticate all users of a database. However,Oracle permits use of all methods within the samedatabase instance.


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A user should be totally unaware of whether or not the database isdistributed (whether parts of the database exist in multiplelocations).

In order for Oracle to achieve this rule, it utilizes the following

system:-Distributed Warehouse Management System

The Oracle Warehouse Management System (WMS) is an integralpart of the Oracle E-Business Suite comprised of transaction sourcesystems, like Oracle Purchasing and Oracle Order Management, andexecution systems, like WMS, residing and operating within the

same instance. This integrated solution eliminates the need for reference and

transaction data integrations which are typically required whenWMS is implemented as a "bolted-on" solution (that is, installedindependent from the E-Business Suite).


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Features of the Distributed Warehouse Management

System

Distributed WMS can integrate with any host system

including legacy systems, other ERP systems like SAP, oranother Oracle ERP system.

Distributed system is an independent WMS solution with

minimal setup requirements. It supports all the routine

warehouse and inventory functions currently available in

the E-Business suite.

Distributed system is a pure execution system without any

costing or accounting implications of material

transactions. The financial implications of the transactions

are maintained in the host system.

The distributed system executes the transactions and

sends the confirmations back to the host system.


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Any change management supported for the

transaction documents like sales orders and

purchase orders in the E-Business Suite issupported in the Distributed WMS system.

Distributed WMS solution can send inventory

adjustments or current on-hand inventory

snapshots to the host system as needed.

The profile option WMS: Deployment Modeis set

to identify the instance as distributed.


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Setting Up the Distributed Warehouse Management System

Oracle Distributed Warehouse Management

System (Architecture and Solution Overview) Oracle Distributed Warehouse Management

System (Setup Document)


System (Technical Implementation)


System (Integration)


System Post Patch Application Steps

EBS 11i10 to Distributed WMS Integration paper


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Basically means that it should be possible to do everythingyou want with the DBMS using the standard set of abstractcommands, e.g. SQL. It means that in certain situations youdon't have to resort to "special" code to do what you want - infact, that no such facility exists.

The advantage of implementing rule 12 properly is that theDBMS's underlying physical implementation is independent ofthe interface, and may be changed at will.

For example, in Oracle I can write "hints" in SQL code that

request the DBMS to run a query in a particular way. If Oraclechanges the way it does things, the idea is that my code willstill run without error (hopefully, better).


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Oracles databases tends to be backwards compatible. Very new release contains a documentation that is user

friendly to learn those new features.

Offers a powerful combination of technology andcomprehensive, pre integrated business apps, including key

functionality built specifically for particular organizations i.e.banks.

With new release users have better capabilities with improvedperformance than previous versions while still maintaining oldfeatures in 8i there was Java compatibility and large database

partitioning, in 9i the features were maintained while newfeatures were added to help the DBA handle change databaseconfiguration.

Oracle responds very well with demanding environment. Itpasses the acid test, important in ensuring integrity of data.


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It supports atomicity thus result of transactions are eithercommitted or rolled back.

Its consistent. Database is transformed from one valid state toanother. Illegal transaction not allowed and if integrityconstraints cant be satisfied transaction is rolled back.

Isolation .result of a transaction are invisible to othertransaction until the transaction is complete thus increasingthe security on data.

Durability .Once completed the result of transaction arepermanent and survive future system and media failures thus

ensures maintenance and protection of data. Oracle 10g has flashback technology for restoring data lost

through accidental user transaction or hardware failure.


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Price, the single most expensive Enterprise Database

Software on the market (but for a reason, it is the best).

Bulky software bundles. Most installations (sometimes 5-

10 on one server) have similar tree structures, all

containing the same java/Perl /etc files, scripts. Most of

them have not been changed since 9i.

High performance system requirements.

Takes longer to learn and is not that simple.


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In summary, most of Codd's ideas have been

implemented, but not all - there is a new DBMS in

development currently that purports to support all of

them, including full view updateability. It remains to be

seen whether it becomes a commercial success.


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Database Management System Oracle Sql An.html?

books.google.co.ke/books?isbn

Dr. Coddsrules for RDBMS

http://www.ask.com/questions-about/Codd's-Rules-Oracle

http://www.webopedia.com/TERM/C/Codds_Rules.html

http://www.oracle-dba-online.com/sql/Codd_rules.htm.

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