This availability of data means specifically, the structure data, and this structure works

To organize documentation fields that simplify access to information.

Due to the growth of the Internet in general and the Web in particular, which has become

Includes billions of pages in various disciplines distributed on different sites, then that was

It represents a difficulty for the researcher in the various disciplines distributed over the different sites, so that was

It represents a difficulty for the researcher in searching and navigating between millions of websites and billions of pages, unless

The display of these sites and pages is characterized by an organization that guides the researcher to the starting points of the search

Way, search and roaming paths to reach target information. This was not achieved in

The main feature of the Internet for a long time was the lack of methods of organizing the network

Information, and facilitate access to it, so the Internet pages were independent in terms of data

Isolated from each other, which was called the Internet chaos.

The regulation, which has become undertaken by specialized agencies, aims to build digital databases on the Internet

The network meets the beneficiaries' knowledge and scientific needs, and facilitates access to this data or

The information is accurate, and in the limited time, without much effort in searching and roaming.

This organization is embodied in the existence of general and specialized databases, and multiple search tools

That achieve the research objectives with accuracy and ease and with less time and effort expended. (Muhammad Abdul Hamid 2005: 156)

From the above, we will deal with the definition of databases, their importance, functions, components, types, and systems

Databases and their components, database management systems and their basic functions, and identification of tools

Research and the importance of digital databases in building search engines.

Definition of databases: Base Data

Databases are defined as a set of related and related data arranged in a specific way

So that it can be searched and updated easily and data redundancy is avoided.

In addition to distinguishing this data with relative independence from the programs responsible for the treatment of this

Data, and independence from programs is an important point of use when developing and restoring systems

Restructuring when new requirements are needed or building a new system

The digital databases on the network are known as:

A group of related and organized data in an accessible electronic form

And processed using specialized computer software.

Database Systems Database

A database system is a statistical system for filing and recording. In other words, it is a computer system

Its general purpose is to store data and allow users to retrieve and update this data at

. To her need

Components of database systems

Database systems consist of several components that aggregate to form an integrated and interdependent system

As follows:

 Data

Data is the point on which all components of database systems work.

All data is entered and stored in a single database. In larger systems it will be all

They are intertwined and shared.

Hard Ware & Hardware Accessories

The hardware components and accessories for the system consist of:

Secondary storage devices: They are mostly magnetic disks, which are used for storage

The stored information and its connection to the various devices and disk drives ... and others

Hardware associated with a master memory that is used to support system software implementation of a base

data.

Soft Ware Software

Whereas the database helps in achieving a set of goals affecting activities

In the main areas of automated data processing applications, specific systems are required to be organized and managed

The stored data, therefore, it is imperative to provide a number of programs that include the special software systems

Databases in addition to programs for personal computers and networks.

One of the most popular programs is the Systems Management Database

All the requirements for accessing the database are handled through the base management system

Data "and give the necessary facilities to add or delete files or columns in order to retrieve or

Update information in such files or tables, and so all these facilities are provided

Using a database management system.

Database management systems

Database Management Systems (DBMS)

A database management system is defined as: (a program whose function is to make compatibility between

The database and the user where this system manages all the requirements of the database business), and so it remains

The user is independent from the physical details of the database files and their location and format. (Dictionary

It is the development of file management systems such as these systems that control the structure or construction of the database

As well as controlling access to the data stored in the database

Create a new database: The Database Management System (DBMS) when creating a database

New data allocates disk storage space for the database as it links storage space

With the programs in the system.

It also allows the user to define the database in terms of files, relationships, and fields within each

File. In addition to specifying the field name, length, and type.

Adding new records: DBMS allows the user to add new records to

Database and the command used in this differs according to each system.

Correction of data: Database management systems allow the possibility of correcting data of any record, as well

Any system allows the user to specify the record or records to be modified, and systems management rules are distinguished

Data with its ability to modify a specific field in a number of records or in all records within the same

Sorting data: Most database management systems provide the user with two methods for arranging records, namely

Storing, Indexing, and Sorting all change physical locations

For records in the file and arranging them according to the data of a specific field.

 Searching for specific data: The Storing process usually follows the search process

A specific data unit, using logical equations to define search terms.

 Print reports: The report is the list of data to be retrieved from the database on the screen

Or the printer.

4- Procedures

It is a set of instructions that represents the processing and design mechanism for databases

The procedures include:

Method of using the system.

Method of operation and implementation.

The method of communication between the user and the system in the various stages of the system.

Users

There are four categories of users, which are divided according to their academic rank, and where it is the first

The highest functionally and practically in the viewpoint of database users and then ranks.

First: the database manager

The database manager performs the following tasks:

1- Determine the database requirements of programs and equipment.

2- Establish working mechanisms to reach user requirements.

3- Specifying the conditions of security and confidentiality, in addition to specifying the terms of reference for use.

4- Putting in place an appropriate work structure that ensures the ideal performance of the system.

5- Control and coordination.

Second: Database designer

A database designer performs the following tasks:

1- Determine the nature of the stored data.

2- Determine the mechanism of communication between the users and the system.

3- Databases are designed in a way that ensures access to user requirements with minimal errors and development

Order in the future.

Third: the database programmer

The database programmer performs the following tasks:

Writing database application programs in some programming languages ​​such as: COBOL languages

, I / pl ++, c, Java "or some of the higher levels of the fourth generation language.

Implement software to make sure there are no errors.

Designing and constructing screens (interfaces) to communicate with users for input and output.

Design and build reports

- Configure applications on the network and their purpose to allow the user to access the database from the Internet

Workstation on the network, or from another party.

Translating database designs into a format in which designs can be represented using languages Database systems.

Fourth: the user of databases

Divides database users into:

- The primary user: This user does not have any previous experience.

Expert user: This will have a long experience in dealing with database systems.

 Database users are the ones who interact with the system from network workstations or points

Any user can access the database through one of the existing applications

On the web.

Database functions

Database management systems share a set of functions that can be summarized as follows:

1- Adding a new information or statement.

2- Delete old data that is no longer needed.

3- Changing existing data according to information that has been created.

4- Search files for specific information or information.

5- Arrange and organize the data within the files.

6- Calculate the final sum, subtotal, or arithmetic average of required data.

Database components:

The database consists of four components:

 Tables

It is the main element in all databases, and it contains data arranged in records

And fields.

A- Record: It is a single line of the table that contains a group of

Related Fields, or in other words, is the set of data stored in the fields that belong to an object

One. The record is the current unit of data that provides us with correct information

With a specific event or topic, it is treated as one unit.

B- Field data: it is a specific element inside the record and it is related to a special type of information

It can be said that it is the primary language in databases, and it is intended for storing a single statement or

One piece of information.

Example: Data fields for a specific book (book name / author / publisher / publication date ...)

Field properties:

- Name Field: gives a name for the field to programmatically use.

- the type of field: it means that each field has its own type according to the data that will be stored

Field, for easy handling of its contents. The types of fields are divided as follows:

Text: a regular type of text that may contain numbers, letters, and symbols (for example

Addresses, serial numbers, and phone numbers). The text field can contain up to 255 characters.

• Memo: Plain text, but it differs from the previous type in terms of the maximum length

The field can be written as large as half up to 64,000 characters. Use this type

For description, comments, and note taking.

• Number: a regular number (not a currency or date).

Date / time / date: regular date or time.

Currency: A number formatted to represent an amount of money. The field is used to avoid

Rounding numbers, it is accurate to 15 digits north of the decimal point and 4 digits to the right of it.

• Auto Number: It automatically puts a serial number in this field as soon as one is filled in

Records in the table

Boolean No / Yes: The answer to a question that assumes right or wrong. This type contains

On one of the two values ​​(yes or no (,) true or false).

Object OLE: A special type of field used to store an object in another program

Such as images and graphics created by other programs, such as Draw MS, or acting

Graph MS, but you want to link it with or embed it with your database.

- The size of the size field: it is intended to determine the size of the data that the field will carry.

Databases use a series of tables to store data, and each table contains

Information for one topic, and each table has a unique name for it.

2- Form

It may be called a GUI (User Interface Graphical) and is usually created to assist the user with

Enter data into database tables.

3- Query

It is used to extract specific data from a table and is written in SQL, and it is considered a result

The query is a sub-database, and once the analyst gets the sub-database in

Image text files, the analyst takes the information in them and puts it into their program,

And extract reports for decision-makers.

 Report - 4

A written presentation of a data analysis and it may be as simple as a list of records with sub-totals

Like other arithmetic relationships between elements of this data.

Foundations and criteria for classification of databases:

There are many standards developed by experts, on the basis of which the databases are classified,

And finally settled on three groups of criteria as follows

1. A. criteria for building structuring

Database programs are usually built according to levels of abstraction or models for databases,

It is intended to bring the composition of the data closer to the taxonomic nature, and therefore it is classified according to the method that is:

It works with it, in other words according to the construction, installation or design and in accordance with these types of standards

There are three types of database combinations:

Hierarchical structure:

It is the dependence of the relationship of the pyramid between the data elements, such that each element is responsible for

Only one item and nothing more.

Structural structure (grid):

It is the adoption of the relationship of the organizational structure between the data elements, such as that there are two classified elements

Under one item or its dependents.

Relational structure:

It is the dependence of a specific relationship between the data elements, for example that the value of the element is dependent on

The sum of two elements, and this combination is one of the most successful structures applied in the world of databases.

This is because it is given a variety in the type of relationship between the data, because the probability of implementing relationships in it is greater than

Any other installation.

Based on this classification, the databases are divided into the following types:

First: Databases Hierarchy

It is data related to each other in relation to one with all, as the information is included in this

The type of databases according to their importance, in a hierarchical manner, starting from the head that branches out into branches

They are interconnected, each of which has an axis that also bifurcates into branches, and so on until it ends at the base. And this

The type is shown in the following figure

Figure (1) Hierarchical Databases

Second: Databases Network

  A network data structure consists of a set of nodes or anchors that are called hubs

Nodes and Branches, as in the aforementioned hierarchical structure, except that they differ in this

The axis is that one outcome may have more than one parent, meaning that the relationship between the data may be

One-to-many or many-to-many, forming interconnectedness in the form of a network.

This type is shown as follows:

Figure (2) online databases

The lattice structure is similar to the structure used in the previous hierarchical structure, and the main difference is between

The two structures is that the hierarchical structure uses a link between parent and child. As for the base structure

Network data, the branch has more than one origin and unlike the hierarchical structure, the network structure

Uses records and relationships between data that are represented by connections

Grid data structures eliminate redundancy problems, but a change in each base may result

Data to be re-structured to restructure the database. New groups can be added easily by creating

New data units, and linking them with existing data.

 The operation of the first and second types is limited to large computers, because the method of organizing the data

It needs large areas of data storage media, and needs detailed and in-depth programming knowledge

Usually, you need one of the advanced languages ​​for programming it, and for this it is difficult to learn and program, and it must

Familiarize the user with detailed knowledge of how the data is structured.

Third: Database Relational

It is one of the most common databases used with personal computers, and it is also used with computers

Mainframes Large, which is more widely used because it requires no memory or media

Bulky storage like other types that work on large computers, and it is easier to store

Learn it and program it. This type of database uses the tables method to represent data.

 The table is the basic unit of any relational database, where the existing data is stored

With these tables, each table is assigned a unique name or address, and fields become the primary key in each

A table and tables are linked to the common fields in each of them. To have relationships between them this relationship be

It is previously known and clear within the data of the table itself, and that determines the reason for calling it a database

Relational, and these tables are used to retain information. That is, relational database systems are

That receives data from the user in the form of tables.

This type is shown as follows:

In addition to the previous classifications, the importance of the method of processing and storing data within cannot be overlooked

Databases Among the most popular database systems are the following two methods

Database Server File

This type of database depends on the files being available for sharing from a specified number of

Users at the same time, and it also allows the possibility of searching and obtaining information quickly, namely

Sufficient for the needs of the average user and for small networks that do not use large amounts of data

Among the most famous databases in this field are those on personal computers such as

. And others, ... Fox Pro, dBase, Clarion Paradox, File Maker Pro

Relational databases:

Relational Databases Management System RDBMS

As mentioned previously, they are strong databases that work more efficiently, and can accommodate a large amount of

The data is much larger than what the first type databases can handle, the most famous of which are those types:

. And others ... Oracle, Sybase Informix, Microsoft SQL

B- Standards specific to the job

When classifying databases according to the job, we find that there are several types, including:

Individual databases are a collection of standard files that are used by an individual

Only one, microcomputer users can each create a database

Its own, using common database management software, the information is stored in

The hard disks of their personal computers, as well as there are other individual databases assigned

For personal information managers and helps them track and manage the information you use on a daily basis

Regular such as addresses, phone numbers, jobs and general notes.

Shared databases are the databases that are shared by workers in a company or

A specific institution in one location, and the company related to this database may store the data in a computer

Mainframe server type. For example, operators log into the database on

Via LAN through terminals or minicomputer, the base is often managed

Data, which coordinates activities and needs related to the base, and defines features

And the priorities of access to the base, and set specifications and general guidelines for use, and be responsible

On information security and preservation Databases distributed on a group of computers, in which data are stored in different locations,

They are connected with each other by networks operating with Server / Client technology

Computer locations are sometimes far apart, overseas, for example, and such rules may be linked by

The Internet, as if a company has a general center in one place, and branches distributed in other locations.

Public public databases which are available to users and beneficiaries of the general public, to whom

He searches for specific information, for example, he just has to resort to the browser that performs the search on a network

The Internet, where the user checks hundreds of websites to find the required information, and on

On this basis, many of these sites represent public databases.

C- Standards for content

The quality of the content is one of the criteria used to classify databases, and when this is used

Standard We find there are several types of databases such as the bibliographic databases that contain

Basic metadata, which reflects descriptive and objective indexing and indexes

And abstracts of information, they do not lead the researcher to the information in its textual form directly, but rather

Know him what is published and available from sources about the field he is searching and searching for, and from models

Such rules include the ERIC Educational Base, MEDLINE Medical Base, and the Database

AGRICOLA AGRICOLA, which is one of the most important global bases, which works on the analysis

The indexing and retrieval of the intellectual output of the aforementioned disciplines.

There are reference databases that act as important collections of reference information

Researchers and the recipient need it to answer their inquiries, such as: dictionaries and glossaries

The rules of directories of names, the rules of encyclopedias and the circles of knowledge and the rules of the path, and translations,

And other reference rules, and numerical and statistical databases that include population statistics

Or various other statistics, researchers need to refer to.

Finally, there are full-text databases of documents, in addition to quotes and data

The required and specific definition of the material to be described, entities of author, title and publisher

And headings of topics or descriptors and abstract, and this type of grammar is constantly increasing, after

If researchers and users found that the bibliographic databases were not adequate, and after they were expanded

Computers storage capacity, and on this basis:

Full-text rules are the texts of sources that are stored electronically, such as newspaper rules

Magazines, articles and books.

As is the case with devices and equipment, the company needs to choose the appropriate database for it

In terms of the structure, function and content in light of the nature of the work that it carries out, and the objectives that it has

She set it for herself, and what was available to her of the potential

Relationships in databases:

As it has been explained previously, relational databases often contain a group of

Tables that are related to each other by a set of relationships, so that data can be accessed

And complete it to obtain the required information. It can be said that the relationship in a simple way is

A relationship between two tables in the database by a specific field that links the data of the two tables.

Link between database tables:

 The two tables in the database are linked by a specific fixed field so that the value does not repeat

The field in the main table and the likelihood of its presence and occurrence in the suitable.

The main table is called the parent table, and it contains most of the data

the basic. While the sub-tables are called Table Child.

In order to find or create a relationship between two tables, we must create two keys, which are the primary key

 . Foreign Key and the Primary Key

Types of relationships in the database:

There are three relationships between the tables and the database

               Provided by: Maher Abdel Fattah Issa