Part Three Database Management System
Passage A Database Basics
The database is now such an integral part of our day-to-day life
that often we are not aware we are using one.
Our entire world is based on information. The telephone book,
the schedule of a sports team, and a university’s timetable are all
different types of databases. They take information and organize it in
such a way that we can extract any information that we desire and
act upon that information. Some databases are simple, such as a
phone list; other databases are so large and complex, they need
computer space greater than 100 PC’s combined. Databases can
simplify our work and our lives by keeping us organized.
Part Three Database Management System
1. What is a Database?
Databases are designed to offer an organized mechanism for stor
ing, managing and retrieving information ( 检索信息 ). [1] They do
so through the use of tables. If you’re familiar with spreadsheets ( 电
子数据表 ) like Microsoft Excel, you’re probably already accustome
d to storing data in tabular form ( 表格形式 ). It’s not much of a stret
ch to make the leap from spreadsheets to databases.
Tables
Just like Excel tables, database tables consist of columns ( 列 )
and rows ( 行 ). Each column contains a different type of attribute
( 属性 ) and each row corresponds to a single record ( 记录 ).
Part Three Database Management System
For example, imagine that we were building a database table
that contained names and telephone numbers. We’d probably set u
p columns named “ID”, “FirstName”, “LastName” and “Telephon
e”, then we’d simply start adding rows underneath those columns t
hat contained the data we’re planning to store, if we have 50 empl
oyees, we’d wind up with a table that contains 50 rows. Figure 3-1
is a sample of table.
Database
A Database include some tables, and you’re able to manipula
te ( 操作 ) data: Retrieve all records that match certain criteria, Up
date records in bulk, Cross-reference records in different tables, Pe
rform complex aggregate calculations. You can see Figure 3-2.
Part Three Database Management System
Figure 3-1 Sample of table
