WHAT IS A DATA BASE:

WHAT IS A DATA BASE:
One of the databases is a "warehouse" that allows us to store information in an organized way that we can then easily find and use.
Databases The term was first heard in 1963 at a symposium in California, USA. A database can be defined as a set of related information that is grouped or structured.
At present, due to technological development in fields such as computer and electronics, most databases are in digital format (e), which offers a wide range of solutions to the problem of storing data.
FEATURES B.D
 Allows to view only the records of the database when the user entered a number of records in it.

 Sets the editing rights. You can add entries teachers and students, if allowed in the database. This

does not restrict the display of your tickets for all.

You can limit the maximum number of tickets for each participant.

 We let you add comments to the entries in the database.

Concurrent access by multiple users.

 Access security and audit.
 Data Independence. This means that the data does not depend on the program and therefore any application can make use of the data.
 Redundancy Reduction. We call the existence of redundant duplication of data, reducing it to get a higher maximum use of space and also prevents any inconsistencies exist between the data. Inconsistencies occur when we find conflicting data.
 Security. A SBD should allow us to have a control over the security of the data.
 Usually displayed as a table in a spreadsheet, in which the records are the rows and columns are fields, or as a form.
 Let’s make a list of the database.
 Programming to allow advanced users.

USES OF DATA ARE MULTIPLE BAES AS:
• Make list of data for certain companies or offices as needed.
• Allows different users consider the information as a corporate resource that has no specific owners.
• Data Independence. The data independence implies a separation between programs and data, ie you can make changes to the information contained in the database or access database in different ways, without making changes to applications or programs .
• Elimination of redundant information. Duplicate
• Elimination of inconsistent information. If the system is developed through conventional files, such cancellation shall be operated in both bills file Collection Control System as the file system Commissions bills.
• Allows sharing of information. Several systems or users can use the same entity.
• Maintains the integrity of the information. Only the right information is stored.

BASE MANAGEMENT SYSTEM (DBMS)
Management Systems Databases, are applications that allow users to: Define, create and maintain the database and provides controlled access to it.
The DBMS is the software that interacts with users of the application programs and database.
Some of the most popular DBMS are: SQL, DB2, SLQ / DS, Oracle, Ingres, Informix, Sybase, Paradox, dBase, Access, FoxPro, R, RM / T and RM/V2.
OBJECTIVES OF A DBMS
 Define the database using the Data Definition Language, which allows the structure, data type and restrictions on the data, storing it all in the database.
 Separate the description and manipulation of data, allowing a greater understanding of the objects, and flexibility of querying and updating data.
 Allow insert, delete, update, query the data using the Data Management Language, which allows to solve the problem presented by the file systems where you have to work with a fixed set of questions or the need for many programs of applications.There are two types of Data Management programs, which differ in the way they access data.
 Procedural languages: manipulate the database record by record and must specify the operations to be performed to obtain the data results.
 No procedural languages: manipulate database recordsets and specifies which data should be obtained as a result without asking the way to go. The language used is no more procedural SQL (Structure Query Language) that has become a standard and the default language of relational DBMS.
 Provide controlled access to the database.
 Security: unauthorized users can not access the database.
 Integrity: maintaining the integrity and consistency of the database.
 Recurrence Control: allows shared access to the database.
 Control of Recovery: restore the database after a failure of software or hardware.
 Data dictionary or catalog: contains the description of the data from the database and is accessible by the user.
 Manage the physical structure of data and storage, providing operational efficiency of the database and access to the storage medium.
 Provide a view mechanism that allows each user to have his own view or vision of the database. The language definition allows us to define views as subsets of the database, allowing:
 Provide a safe level excluding data from being viewed by certain users.
 Allow users to view data in the desired format.
 A view represents a consistent and permanent database, even when the database is to make changes in its structure.
 Eliminate data redundancy, provide minimal data duplication and minimize disk space used.
Provide procedural and procedural interfaces, allowing manipulation by interactive users and programmers.
 Independence between the structure of the logical organization of data (physical independence).
 Independence between the logical description of the database and specific descriptions of the different points of view of users.
 Allow for easy data management.

Entity-Relationship Model
It is a tool for modeling data from an information system. These models express the relevant entities for an information system and their interrelationships and properties.

 

1. It produces the diagram (or diagrams), Entity-relationship.
2. Model is completed with lists of attributes and a description of other restrictions that may not be reflected in the diagram.
Given the rudimentary nature of this technique requires some training and experience to achieve good data models.
Data modeling is not just using this technique. Other techniques are needed to achieve an implementable model directly into a database. Briefly:
§ Processing of multiple binary relationships.
§ Standardization of database relationships (some relationships can become attributes and vice versa).
§ Conversion tables (in case of using a relational database).

Relational Database
Is a database that conforms to the relational model, which is themodel currently used to implement database already planned.Allow to establish interconnections (relationships) between the data (which are stored in tables), and through those connectionsrelate the data from both tables, hence its name: "Relational Model".
Features
§ A relational database consists of multiple tables or relations.
§ There can be two tables with the same name and registration.
§ Each table is itself a set of records (rows and columns).
§ The relationship between a parent and a child table is carriedout through primary and foreign keys (or foreign).
§ Primary keys are the primary key of a record within a table andthey must meet the data integrity.
§ Foreign keys are placed in the child table contain the same value as the primary key of the parent record, by means of theserelations are made.