Chapter 12 DATABASES

Chapter 12

DATABASES

      Through this article we may understand many information about the database.In fact, I also understood from the internet to about the database.The database is defers to the construction of data to organize, the memory and the managerial data warehouse, it produced is 50 years ago, along with information technology and market development, specially after in the 1990s, the data management no longer merely was the memory and the managerial data, but transformed each data management way which the user needed. The database has many types, the memory had each kind of data form from the simple to be able to carry on the large-scale database system which the mass data saved in each aspect to obtain the widespread application.

Introduction　　                                                                                       

Strictly speaking, the database is “organizes, the memory and the managerial data warehouse according to the construction of data”. In management of economy's routine work, needs to admit frequently certain related data such “the warehouse”, and needs to carry on corresponding processing according to the management. For example, the enterprise or Institution's Personnel must this unit staff's basic situation (staff number, name, age, sex, native place, wages, resume and so on) deposit frequently in the table, this table may regard as is a database. Had this " Data warehouse " We may according to need momentarily to inquire some staff's basic situation, may also inquire the wages in some in scope staff population and so on. If these work can carry on automatically on the computer, then our personnel management may achieve the extremely high level. In addition, in the financial control, the storage management, production management also needs to establish numerous this kind of " Database " , enables its to be possible to realize financial, the warehouse, the production automated management using the computer.And the database is defers to some kind of data model to organize and deposits in the second-level memory's data acquisition. This kind of data acquisition has following characteristic: It is not as far as possible redundant, serves take the most superior way as some specific organization's many kinds of applications, its construction of data independence in uses its application procedure, increases to the data, deletes, changes with the retrieval by unifies the software to carry on the management and the control. Looked from the development history that the database is the data management higher phase, it is develops by the document management system.So the database is a long-term memory in the computer, organized, has sharing, the global administration data acquisition.

In database data nature

1. data integrity: The database is a unit perhaps an application domain conventional data processing system, what he saves is belongs to the enterprise and the enterprise department, the association and individual related data set. In the database data is embarks the establishment from the total view, he carries on the organization, the description and the memory according to certain data model. Its structure based on data natural connection, thus may provide all essential access path, and the data no longer aims at some application, but faces the entire organization, has the whole structurized characteristic. 　

　

2 data sharing: In the database data is shares its information for the numerous users to establish, already got rid of the concrete program limit and the restriction. The different user may according to the respective usage use database in data; Many users may simultaneously share in the database the data resources, namely the different user may in the simultaneous access database identical data. Not only data sharing has satisfied various users to the information content request, simultaneously has also satisfied between various users the message communication request.

DBMS Structure

   We knew that DBMS is designed and in logic constructs or the data which arranges is used together.DBMS Structure may divide into 5 kinds is:Hierarchical DB, Network DB, Relational DB, Multidimensional DB, OODB

   The hierarchical structure model materially is one kind has the root node directional ordered tree (in mathematics " Sets up " By the definition is the connection chart which not returns). The next chart is a College organization structure drawing. This organizational structure image tree, the school is the tree root (is called root node), each is, the specialty, the teacher, the student and so on (is called point) for a spot, side tree root's is called with spot between contacting, the tree root ratio of with the side is 1:N, namely the tree root only then, the branch has N.

The Network database is called the netted database system according to the lattice construction of data establishment's database system, its typical representative is DBTG (Data Base Task Group). May transform with the mathematical method the lattice construction of data as the level construction of data.

 The relational database is a database system which is composed of the relations construction of data is called the relational database system.The relationship construction of data sums up some complex construction of data as the simple binary relation.In the relational database, establishes nearly completely to the data operation in or many relational forms, through to these relational operations and so on form's classification, merge, connection or selection realizes the data management.

  The Object-oriented is one understanding methodology, is also one new programming methodology. Unify the object-oriented method and the data bank technology may cause the database system's analysis, the design greatest degree with the people to the objective world understanding consistent. The object-oriented database system is to satisfy the new generation database system which the recent database application needs to produce.

 The Multidimensional Database may the understanding be simply: Stores the data in a n Uygur array, but is not form depositing which relational database such records likely. Therefore it has the massive sparse matrices, the people may through the multi-dimensional view observed data. The multi-dimensional database increased a time Uygur, compares with the relational database, its superiority lies in may raise the data processing speed, speeds up the reaction time, raises the inquiry efficiency.

Website database safe hidden danger

Causes the reason which the security problem exists to cause the electronic commerce website database existence safe hidden danger the reason mainly to display at present in the following several aspects:

(1)    the user is not correct to the database visits, causes the database data mistake;

(2)    for some kind of goal, destroys the database intentionally, enables it to restore;

(3)    the illegal visit should not visit database information, but not scar;

(4)    the user when carries on the database visit through the network, has the possibility receives each kind of technology (for example wiretapping and so on) attack;

(5)    the illegal user bypasses the security kernel, steals phenomena and so on information resource; (6) without authorization the illegal revision database data, cause its data to lose authenticity and some one.