Database Reference
In-Depth Information
Choosing Between a Spreadsheet and a Database
If databases are much like spreadsheets, why do people still use database applications? A database is
designed to perform the following actions in an easier and more productive manner than a spreadsheet
application would require:
•
Retrieve all records that match particular criteria
•
Update or modify a complete set of records at one time
•
Extract values from records distributed among multiple tables
Why Use a Database?
The following are some of the reasons why you would use databases:
•
Compactness
:
Databases help you maintain large amounts of data and thus com-
pletely replace voluminous paper files.
•
Speed
:
Searches for a particular piece of data or information in a database are
much faster than sorting through piles of paper.
•
Less drudgery
:
It is a dull work to maintain files by hand; using a database com-
pletely eliminates such maintenance.
•
Currency
:
Database systems can easily be updated and so provide accurate infor-
mation all the time and on demand.
Benefits of Using a Relational Database Management System
RDBMSs offer various benefits by controlling the following:
•
Redundancy
:
RDBMSs prevent you from having duplicate copies of the same data,
which takes up disk space unnecessarily.
•
Inconsistency
:
Each redundant set of data may no longer agree with other sets of
the same data. When an RDBMS removes redundancy, inconsistency cannot
occur.
•
Data integrity
:
Data values stored in the database must satisfy certain types of
consistency constraints. (I'll discuss this benefit in more detail in the section
“Understanding Data Integrity” later in this chapter.)
•
Data atomicity
:
In event of a failure, data is restored to the consistent state it
existed in prior to the failure. For example, fund transfer activity must be atomic.
(I'll cover the fund transfer activity and atomicity in more detail in Chapter 6.)
•
Access anomalies
:
RDBMSs prevent more than one user from updating the same
data simultaneously; such concurrent updates may result in inconsistent data.
•
Data security
:
Not every user of the database system should be able to access all
the data. Security refers to the protection of data against any unauthorized access.
