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Answered 2008-10-01 05:33:39

hows the btec national going..... by the way you cant get away with copy and pasteing....

ps: this is unit 5 of the btec natinal (soft-dev )

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Explain how records and related records are deleted to ensure the integrity and consistency of the database is maintained?

Do it yourself. P.S Im a BTEC National Teacher.

Why is it desirable to enforce the referential integrity rules and entity integrity rules?

Database Management Systems ensure consistent data if the database is modeled using proper referential integrity. For example, if a Customer record is deleted from the system, all Orders and Order Items pertaining to that Customer should ideally be cleaned up. Same thing is true for a specific Order. Such logic need not be in the application, instead you can set up database referential integrity rules to perform these cascading actions automatically for you.

What is the concept of recovery?

There is command in database to delete the data from a table . But what if the data you have deleted was important ? For this there are commands in database system to recover the data. This is what is called data recovery .In database the data can be deleted ,what if the deleted data was important. In that case we use commands like rollback and save point.

What is Referential Integrity?

Referential Integrity is a set of rules that a DBMS (Database management system) follows to ensure that there are matching values in the common field used to create the relationship between related tables and that protects the data in related tables to make sure that data is not accidentally deleted or changed.

Why is it important to maintain the integrity of relationships between tables?

Because it prevents related data from being change or deleted.

Advantages and disadvantages of manual database?

ADVANTAGES OF MANUAL DATABASE-It is cheaper-It dosen't consume alot of electricity-You can be exercised-It can't be deleted easilyDISADVANTAGE OF MANUAL DATABASE-It is not that secured-It is harder-It consumes a lot of time

What is the differences between moral integrity and ennate integrity?

ENTITY INTEGRITY In a relational database, entity integrity is a property that ensures that no records are duplicated and that no attributes that make up the primary key are NULL. It is one of the properties necessary to ensure the consistency of the database. Entity Integrity ensures that there are no duplicate records within the table and that the field that identifies each record within the table is unique and never null. The existence of the Primary Key is the core of the entity integrity. If you define a primary key for each entity, they follow the entity integrity rule. Entity integrity specifies that the Primary Keys on every instance of an entity must be kept, must be unique and must have values other than NULL. Although most relational databases do not specifically dictate that a table needs to have a Primary Key, it is good practice to design a Primary Key for each table in the relational model. This mandates no NULL content, so that every row in a table must have a value that denotes the row as a unique element of the entity. Entity Integrity is the mechanism the system provides to maintain primary keys. The primary key serves as a unique identifier for rows in the table. Entity Integrity ensures two properties for primary keys: The primary key for a row is unique; it does not match the primary key of any other row in the table. The primary key is not null, no component of the primary key may be set to null. The uniqueness property ensures that the primary key of each row uniquely identifies it; there are no duplicates. The second property ensures that the primary key has meaning, has a value; no component of the key is missing. The system enforces Entity Integrity by not allowing operations (INSERT, UPDATE) to produce an invalid primary key. Any operation that creates a duplicate primary key or one containing nulls is rejected. REFERENTIAL INTEGRITY A database management safeguard that ensures every foreign key matches a primary key. For example, customer numbers in a customer file are the primary keys, and customer numbers in the order file are the foreign keys. If a customer record is deleted, the order records must also be deleted; otherwise they are left without a primary reference. If the DBMS does not test for this, it must be programmed into the applications. Referential integrity in a relational database is consistency between coupled tables. Referential integrity is usually enforced by the combination of a primary key(candidate key) and a foreign key. For referential integrity to hold, any field in a table that is declared a foreign key can contain only values from a parent table's primary key or a candidate key. For instance, deleting a record that contains a value referred to by a foreign key in another table would break referential integrity. The RDBMS enforces referential integrity, normally either by deleting the foreign key rows as well to maintain integrity, or by returning an error and not performing the delete. Which method is used would be defined by the definition of the referential integrity constraint. An employee database stores the department in which each employee works. The field "DepartmentNumber" in the Employee table is declared a foreign key, and it refers to the field "Index" in the Department table which is declared a primary key. Referential integrity would be broken by deleting a department from the Department table if employees listed in the Employee table are listed as working for that department, unless those employees are moved to a different department at the same time. Thanks Nida

What is database software and what does it do?

Data (a CD collection - for instance) can be stored in a database. The data records can be deleted, added to, sorted (by title, artist, etc) or printed on paper (lists) - depending on the user's requirements.

How can you delete your Bellasara account?

I have deleted my daughters account by emailing and writing please remove {account username} from your database. They emailed me back to confirm the deleted account. Hope this helps everyone!

Message confidentiality and message integrity?

When the message transferred from sender to receiver in not added, deleted or modifies by an external third parties, then that message represents the message integrity. Message confidentiality will be added when the message is not been viewed or noted by the unauthorized user. Message integrity and message confidentiality are related to each other. Without message confidentiality you cannot achieve message integrity and vice versa.

Are there any disadvantages to having data linked?

Yes. If your data source is deleted or moved, your spreadsheet or database application will have no data to display.

What does it meand wen it say user misconfigured in database on meez?

it means that your profile is deleted or u either got banded from meez

How data can be edited or deleted from database via php?

if you know SQL language, you can run any command by using PHP's mysql_query() function.

Does having data linked limit the portability of documents?

Yes. If your data source is deleted or moved, your spreadsheet or database application will have no data to display.

What is foregn key?

A foreign key is a primary key or candidate key in the referenced table, it could consists of one or many columns. The foreign key is added to the referencing table. When the foreign keys between the tables are established, the referential integrity relationship in database system is hence maintained. While establishing foreign key in the referencing table, we may impose constraints on the foreign key, the constraint will affect how the referencing table's row behaved when it was updated or deleted in the referenced table or vice versa. There are several constraints, i.e. CASCADE, RESTRICT, SET DEFAULT, SET NULL, NO ACTION. Here is the example, CASCADE - Whenever rows in the master (referenced) table are deleted, the respective rows of the child (referencing) table with a matching foreign key column will get deleted as well. A foreign key with a cascade delete means that if a record in the parent table is deleted, then the corresponding records in the child table will automatically be deleted. This is called a cascade delete. RESTRICT - A row in the referenced table cannot be updated or deleted if dependent rows still exist. In that case, no data change is even attempted. Should not be allowed.

What does it mean when it says User misconfigured in database in meez?

means u page have been deleted But How Come I Can Log In On Internet Explorer But Not On Mozilla Firefox ?

Is there a way to retreve the neopets account you deleted yourself?

Well, when you delete the account, it is probably permanent-which means it is completely wiped off the database... sorry :(

Is it possible to delete a Youtube account when the Gmail account it is connected to has already been deleted?

yes it is possible beacouse in the gmail database there are in no record of that user

What does database monitoring software do?

Database monitoring software should monitor your software. It should also process the health of your pc and issue alerts for any issues that should arise.Database monitoring software makes sure important information on hard drives does not get accidentally deleted. It often also password protects data.

What are two disadvantages of a computerised database?

If you have accidently deleted the data and haven't made a back-up it might be gone so you will have to start it again and It waste's electricity.

How do you recover deleted mails from Microsoft Outlook 2003 without using Exchange Server?

If email has been moved into Deleted Items Folders, then user can retrieve back all the email by simply drag and drop because they are soft deleted items. But, in case of hard deletion or you can say that emails have been deleted from Deleted Items Folders, than user should go for any third party utility which can easily restore database of Outlook PST data file like SysTools Outlook Recovery.

What are the different parts to a database?

There are four major parts to a database. Which are tables, forms, reports and queries.Tables- Where all the information and data is stored within a database.Forms- Forms are used to enter, edit or deleted data in a database one record at a time.Reports- A report makes a paper copy of the data contained within a database.Queries and Sorts- Queries are a special database tool that allows you to search a database for a specific records based on certain information.*Web-based databases are often written in PHP and/or SQL, script languages frequently used by web developers.

What is the difference between truncate and delete in terms of a database transaction?

Once data is truncated it can not be rolled back (recovered). However, data can be rolled back if deleted accidentally.

Does cheat engine work on roblox tix?

You're thinking of Fiddler2, but that doesn't even work. Fiddler2 is a site thing. You'll get deleted as soon as you pass the database.

Is your WikiAnswers account deleted if you don't use it for a long time?

No, old accounts are not deleted - we have accounts still in the database from when the site first began!However, if your account is inactive for a long period of time and another active user would like your username, your account may be renamed.

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