Database

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* Set Database

* Architecture Database

* Structure and models of Databases

* Classification of Databases

* Future Trends

* Difference between DBMS and Database

* Historical development of Databases

* Advantages of Database Processing

* Types of Operating Systems

Database Definition

Is a set of data and structured, stored, and the auxiliary memory and the programs that manipulate data.

ORIGINS:

Emerge in the mid-seventies when Codd proposed the rational model.

ADVANTAGES:

Data independence and treatment (mean change, and change data or program).

Consistency of results (reduce redundancy).

Improved data availability

* No data owner (not equal to be public).

* Not applications or users.

* We save description (Idea catalogs).

Compliance with certain rules, restrictions, security, access and operations.

Efficient storage management.

Architecture Database

It is divided into three levels:

Physical level is the way data is stored, such records. Is associated with the representation of the data, what is known as physical layout, often this is not provided by many MBDS as these do not allow users how to choose and store your data.

Level vision: It is the closest to the users, ie belonging to the way each user sees the data.

Conceptual level: Describes the structure of the entire database to a user community. The conceptual framework hides the details of physical storage structures and concentrates on describing entities, data types, links, user operations and restrictions.

Structure and models of Databases

Relational model: The most commonly used today. Your data is structured in tables:

Each row is a record or entity and each column is a field of this record. It is the most easy to use

A table is called a relationship, and each tuple row, each column of a tuple is called attribute.

Hierarchical Model: A parent can have multiple children but each child can have only one parent.

Structure in the form of inverted tree, where each node can have multiple nodes or children, but a node can have multiple parents.

Network Model: It presents a lot of records together by links. It presents the real world as logical records representing an institution which relate to each other by arrows. Its structure presents more than the form of a tree as a child node in the structure can have more than one parent node.

Distributed Databases: Those that are stored on multiple computers connected to the network, so access to information from different universities or branches of a company, its difficulties are referring to the duplication of data and its integrity when to make updates to them.

Classification of Databases

1. PLEX STRUCTURE: The database has at least one linking many to many (MANY MANY-TO-link “).

2. TREE OR NETWORK: The database has no chaining many to many (“ONE-TO-MANY link”).

TREE STRUCTURE 2.1: By definition, the tree structure (“tree structure”), each child (“child”) has only one parent (“parent”).

2.2 NETWORK STRUCTURE: By definition, the network structure (“network structure”), each child (“child”) can have several parents (“parents”).

For its use and application:

Gridded database: It is very similar to the hierarchical, in this data model are linked by relations of possession but unlike the hierarchical, a dataset can have multiple parents, this model is also known as network model.

Database object-oriented: The scheme is represented by a set of classes that define the characteristics and behavior of objects that populate the database. The difference from the others, is that in traditional operations have to be made in the data are asked to applications that use them.Bibliography: Contains primary source information, author, publication date, title.

Directories: An example and an electronic directory.

Source database: Provides the primary source or document unlike full bibliographic provide just a representation and the primary whip, these are also called database full text.

Numerical: numerical contain information such as census or quantitative indicators.

Textual: Provides full text of a document.

Mixed: Combining numeric and text information.

Object-oriented: It is organized around objects, an object has names and has information and procedures.

Future Trends

Within the future outlook of multiple databases is an important aspect to consider, the unprecedented success of the World Wide Web (WWW or, in abbreviated form, “the web”) as a means of publishing documents and as a means of exchanging information . The WWW provides one of the most heterogeneous and challenging in the field of interoperability. Have recently emerged technologies and standards aimed at making the web a scalable and manageable. One such technology is XML [4] (Extensible Markup Language), on which the scientific community has high expectations. One is that XML is becoming the Internet a database system, making it possible to specify queries in the style of the managers of traditional databases which gives much better results than existing search engines. However, XML itself does not have much of the functionality of systems of multiple databases as indicated in Donaji. The challenge is to integrate that functionality in XML and to maximize the strategic information we find on the web.

DMBS

Is a set of programs that are handling the creation and all access to databases, is composed of:

* DDL: Data Definition Language

* DML: Data Manipulation Language

* SQL: Query Language.

The most common DBMS Oracle, SqSelver, Infomix, Sysbase.

FEATURES OF DBMS:

* Complex queries optimized: Query optimization allows the rapid execution of them.

* Secure access and audit: The right of access to data in the database by individuals and agencies, this is in order to know what or who made a particular change and when.

* Backup and recovery: is ability of a database system to retrieve the information that I had a moment before data loss.

* Access via standard programming languages: refers to the aforementioned possibility of accessing data from a database using programming languages outside the database system itself.

* Control of data redundancy, consists in achieving a minimal amount of storage space to store data without duplicating information

* Maintain integrity: Ensures the accuracy or correctness of the information contained in a database.

* Support for transaction control and recovery of faults: It is known as a transaction is made any operation on the database. Transactions must therefore be controlled so as not to disturb the integrity of the database. The fault recovery has to do with the ability of a DBMS to retrieve information that is lost during a fault in software or hardware.

* Independence of data: data exchange program involves change.

* Hardware Independence: They are available to be installed on multiple hardware platforms.

Difference between DBMS and Database

The database is a collection of organized data, and the same context in a way that is easy to access. A DBMS is a set of programs used for the creation and implementation of databases.

The components of a database are: people, machines, programs and data.

Historical Evolution of Databases

Have their origins in the Apollo project to send man to the moon, in the seventies.

At that time, there was no system that would manage the vast amount of information required by the project. The first project company, NAA (North American Aviation), developed a software called GUAM (General Update Access Method) based on a hierarchical structure.

In the mid-sixties, he developed IDS (Integrated Data Store), General Electric. This work was led by one of the pioneers in database systems, Charles Bachmann. IDS was a new type of database system known as network system.

The hierarchical and network systems are the first generation of DBMS. But these systems have some drawbacks:

* You need to write complex application programs to respond to any query data, however simple it is.

* Independence of data is minimal.

* Do not have a theoretical basis.

In 1970 Codd of IBM Research Laboratories, wrote an article presenting the relational model. Began to develop many relational systems, appearing first in the late seventies and early eighties.

Relational DBMS is the second generation of the DBMS.

At present there have been two new models: the object-oriented data and the extended relational model. However, unlike the preceding models, the composition of these models is unclear. This development represents the third generation of the DBMS.

ONLINE PROCESSING SYSTEMS AND LOTS

Batch processing system: running jobs and organizes memory n fixed portions, each job is loaded into memory when you play your turn and stays in memory until it ends.

Online processing system: It implies that the programs run so that the data is updated immediately in the computer files. This type of processing is also known as real time.

They are indispensable in cases where the data contained in the files are modified several times in the course of a day and almost immediately consult with the modifications that were made. An example of this is a reservation system on any airline.

LANGUAGES 31 o and 4 o GENERATION

They are divided into programs aimed at people and objects.

Business Languages: instruments are developed to be objective, to develop business information systems. For example colobus monkeys.

Scientific languages: They are designed to meet the needs of repetitive procedure, for example Foltran and APL.

Advantages of Database Processing

* 1. Independence and treatment data: the data exchange involves the exchange of programs.

* 2. Consistency of results: logical actions.

* 3. Improved data availability.

* 4. Compliance with certain standards: that is security restrictions (actions and operations)

* 5. Efficient storage management.

4 GL’s THE HANDLING OF DATA PROCESSING.

* Must have an integrated database manager

* You must have an object-based reporter

* There should be total independence between the data and applications

* You must have a data dictionary or repository

* Must provide support for a security scheme for users

* You must have a language-based tracking examples (Query By Example)

* It should emphasize the data model rather than programming code

* Must have tools for easy documentation of analysis, design, and data model.

Types of Operating Systems

MULITAREA:

Allows multiple operations running simultaneously. And the number of programs that can run depends on the available memory of the CPU.

MULTIUSER:

Allows more than one ascent to the computer user, an example is the UNIX operating system, there are three ways to allow multiple people use the same PC at the same time, using modems, wireless terminals via serial ports and using networks.

Multiprocessors:

They are called to computers that have more than one CPU, coordinates the operations of multiprocessor computers, each CPU can be executing an instruction. By using a computer with multiprocessing capability increases the speed of response and processes.