外文文献-中文翻译-数据库

外文文献-中文翻译-数据库

英文原文2:

《DBA Survivor: Become a Rock Star DBA》by Thomas

LaRock，Published By Apress.2010

You know that a database is a collection of logically related

data elements that may be structured in various ways lo meet the

multiple processing and retrieval needs of organizations and

individuals. There’s nothing new about databases—early ones

were chiseled in stone, penned on scrolls, and written on index

cards. But now databases are commonly recorded on

magnetizable media, and computer programs are required to

perform the necessary storage and retrieval operations.

Yo u’ll see in the following pages that complex data

relationships and linkages may be found in all but the simplest

databases. The system software package that handles the

difficult tasks associated with creating, accessing, and

maintaining database records is called a database management

system (DBMS) .The programs in a DBMS package establish an

interface between the database itself and the users of the

database. (These users may be applications programmers,

managers and others with information needs, and various OS

programs.)

A DBMS can organize, process, and present selected data

elements from the database. This capability enables decision

makers to search, probe, and query database contents in order

to extract answers to nonrecurring and unplanned questions (hat

aren't available in regular reports. These questions might initially

be vague and / or poorly defined, but people can "browse”

through the database until they have the needed information. In short, the DBMS will “m anage”the stored data items and

assemble the needed items from the common database in

response to the queries of those who aren’t

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programmers. In a file-oriented system, users needing

special information may communicate their needs to a

programmer, who, when time permits, will write one or more

programs to extract the data and prepare the information[4].The

availability of a DBMS, however, offers users a much faster

alternative communications path.

If the DBMS provides a way to interactively and update the

database, as well as interrogate it capability allows for managing

personal data-Aces however, it does not automatically leave an

audit trail of actions and docs not provide the kinds of control a

necessary in a multiuser organization. These-controls arc only

available when a set of application programs arc customized for

each data entry and updating function.

Software for personal computers which perform me of the

DBMS functions have been very popular. Personal computers

were intended for use by individuals for personal information

storage and process- These machines have also been used

extensively small enterprises, professionals like doctors, acrylics,

engineers, lasers and so on .By the nature of intended usage,

database systems on these machines except from several of the

requirements of full doge database systems. Since data sharing

is not tended, concurrent operations even less so. the fewer can

be less complex. Security and integrity maintenance arc de-emphasized or absent. As data limes will be small, performance

efficiency is also important. In fact, the only aspect of a database

system that is important is data Independence. Data-dependence, as stated earlier, means that applicant programs

and user queries need not recognizant physical organization of

data on secondary storage. The importance of this aspect,

particularly for the personal computer user, is that this greatly

simplifies database usage. The user can store, access and

manipulate data a( a high level (close to (he application) and be

totally shielded from the

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low level (close to the machine) details of data organization.

We will not discuss details of specific PC DBMS software

packages here. Let us summarize in the following the strengths

and weaknesses of personal computer data-base software

systems：The most obvious positive factor is the user

friendliness of the software. A user with no prior computer

background would be able to use the system to store personal

and professional data, retrieve and perform relayed processing.

The user should, of course, satiety himself about the quality of

software and the freedom from errors (bugs) so that invest-merits in data arc protected.

For the programmer implementing applications with them,

the advantage lies in the support for applications development

in terms of input screen generations, output report generation

etc. offered by theses stems.

The main negative point concerns absence of data

protection features. Unless encrypted, data cane accessed by

whoever has access to the machine Data can be destroyed