Journal
Wednesday January 30, 2008
Chapter 9th will be review in today's
class:
The fastest search engine, not jet patented
is on the book, please review it starting on page 284 to page 291 on volume one.
1. the fastest search = fastest database
FILE
HANDLING: A DATABASE
from chapter 9th,
A key feature of the computer is the
ability to store information, and to retrieve it at a later time. The
information (data) has to be saved somewhere, which is called a file, and has to
be under a name, which is called a filename. A program constantly interacts with
the files to store, retrieve, modify or delete the data. Traditionally, a file
that is used to store or retrieve data is called a data file or an
input file. A data file may contain personal information such as the names
of employees, their telephone numbers and salaries.
You may work interactively with a program and
enter the data each time. However, when the input data becomes large, it is
necessary to work with a data file rather than typing the data over and over
each time. One example of a data file would be supermarket pricing, where a huge
amount of data is manipulated. In today’s web engine, hundreds of files may
have to be processed in order to complete a search. The advancement of the
Internet has proportionally increased the number of files and their size. For
any organization, data processing and data manipulation are essential
operations. A database runs the
day-to-day operations by adding new records, searching for particular record(s),
modifying the existing records and generating reports. Due to the real-time
demand of data, the efficiency of databases is subject to review and, as a
result, a tremendous effort has been spent to secure their reliability
1) Information
and data are two different things: according to Dr. Ebrahimi they are the same.
2) An example
of a report is running the particular information, such as # of credits,
salaries, etc.
Information: is data that has
been process so it has meaning and value
Data: refers to raw facts names,
numbers, sounds. (contribution by Farzad)
The IBM Selective Sequence Electronic Calculator
IBM's Selective Sequence Electronic Calculator (SSEC), built at IBM's Endicott
facility under the direction of Columbia Professor
Wallace Eckert
and his Watson
Scientific Computing Laboratory staff in 1946-47, shown here after it was
moved to the new IBM Headquarters Building at 590 Madison Avenue in Manhattan [4],
where it occupied the periphery of a room 60 feet long and 30 feet wide [42]
(Herb Grosch [59]
estimates the dimensions of its "U" shape at 60 + 40 + 80 feet, 180 feet in all,
about half a football field!)
http://www.columbia.edu/acis/history/ssec.html
1.computer stores information, however a calculator does
not.
WHAT IS A DATABASE (dbase)
Manipulating data (information) plays an important role in any organization
today. In order to manipulate the data, information has to be stored, retrieved,
modified or deleted. At any moment new data can be added to a file, or existing
information can be retrieved, modified or even deleted. Instead of one file
there might be several files needed to store information as well as to interact
with other files (file processing). The notion of data manipulation where data
may be stored, retrieved, modified or even deleted is called a database.
In addition, there are times when it is necessary to generate reports based on a
certain request or computations from the database.
what
is bit:
- A bit (short for binary digit) is
the smallest unit of
data in a computer. A bit has a single
binary value, either 0 or 1. Although
computers usually provide
instructions that can test and
manipulate bits, they generally are designed
to store data and execute instructions in
bit multiples called
bytes. In most computer systems, there
are eight bits in a byte. The value of a bit
is usually stored as either above or below a
designated level of electrical charge in a
single
capacitor within a memory device.
from webpage:http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci213816,00.html |
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this is a
picture of a byte according to Bill Parris
01000011 -
A JOURNEY FROM BIT TO DATABASE
Computer
information is represented in binary form using a bit. Each bit contains a
value which is either zero or one. Eight bits represent a byte. Depending on the
system one or two bytes represent a character. Several characters form a field
or a string. One or more fields make up a record. Multiple records build a
stream or a file. Finally several files create a database. However this naming
convention may vary slightly, a string may represent the whole file or a
database may contain only a single file.
BUILDING A SIMPLE DATABASE: Create,
Display and Search
The
following program illustrates how easily you can build a simple database by
putting a few functions together. For the sake of simplicity, the database
program will add, display and search the data immediately, with data
modification and deletion performed later. In writing this program, the concern
is simplicity rather than efficiency (speed of program or saving space). The
three functions for this database are myappend() to add a record to the
end of data file, mydisplay() to display entire records, and mysearch()
to search for a particular record.
ASSIGNMENT 3
Due for next class.
Create a database for a student information system consisting of
a file with several records. Each record will consist of the following 6
fields. The database will be extended later on to use several files, with
each file dedicate to a purpose.
1) First Name
2) Last Name
3) Id Number
4) Email Address
5) # of Credits
6) Major
You can create it using any language/database type you like.
