data base final

importing or for exporting.  One inflexibility noted was that when copying files the two files must have the exact same fields in the same order as the master file.  This can be problem if you want to copy identical fields from different files.

Forms design is simple but tedious.  Although it may seem flexible to be able to paint the screen in any manner that you wish, it can be time consuming because no default screen is available.  Like other database management systems, the usual syntax for defining fields apply, field name followed by the length of the field in braces.  However, editing is a little more difficult.  Changing the form can be done by inserting and deleting, one character at a time.  Omnifile does not support moving fields around, nor inserting blank lines.  This means that if a field was to be added at the beginning of the record, the entire record would have to be re-entered.
Records are added and viewed in the format that the user first designed it.  Invalid entries are not handled very well.  Entering an illegal value in a certain field results in a beep and no message, the user is left there to try and decide what the error is.  Omnifile does support the ability to insert new records while viewing existing records and to make global or local changes.
Querying can be performed by using an index or using a non-indexed search.  If a search for a partial entry is made like ARob@ instead of ARobinson@, a message is then displayed stating that not an exact match was found.
Overall
These are just a few of the database programs that help start the whole database management system era.  It is apparent that DBMS=s today still use some of the fundamentals first implemented by these >old= systems.  Items like menus, forms, and portability are still key parts to current applications.  However, programs have come along since then, but still have as their bases the same fundamental principles.

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data base 3rd

unmarked.  The only way to correct this is to start over and enter everything again.  This is time consuming and obviously inefficient.  Although the menus are helpful and guide you through the stages or levels, there is the option to turn off the menus and work at a little faster rate.
DBaseIII=s command are procedural (function oriented) and flexible.  It utilizes many of the common functions like:
select records
C. select fields
C. include expressions ( such as calculations)
C. redirect output to the screen or to the printer
C. store results separately from the application
Included in dBaseIII is a limited editor which will let you create commands using the editor or a word processor.  Unfortunately, it is still limited to certain commands, for example, it can not create move or copy commands.  It also has a screen design package which enables you to design how you want your screen to look.  The minimum RAM requirement of 256k  for this package really illustrates how old this application is.  The most noticeable problem documented about dBaseIII is inability to edit command lines.  If, for example, an error was made entering the name and address of a customer, simply backing up and correcting the wrong character is impossible without deleting everything up to the correction and re-entering everything again.
DBaseIII is portable and straightforward to work with.  It allows users to import and export files in two forms: fixed-length fields and delimited fields.  It can also perform dBaseII conversions.  Creating file structures are simple using the menus or the create command.  It has field types that are still being used today by applications such as Microsoft  Access, for example, numeric fields and memo fields which let you enter sentences or pieces of information, like a customer=s address, which might vary in length from record to record.  Unlike Condor 3, dBaseIII is able to edit fields without having to start over.  Inserting new fields or deleting old fields can be done quite easily.
Data manipulation and query is very accessible through a number of built-in functions.  The list and display commands enable you to see the entire file, selected records, and selected files.  The browse command allows you to scroll through all the fields inserting or editing records at the same time.  Calculation functions like sum, average, count, and total allow you to perform arithmetic operations on data in a file.  There are other functions available like date and time functions, rounding, and formatting.

Omnifile
Omnifile is a single-file database system.  This database is form oriented meaning that it has a master form with alternate forms attached to it.  Therefore, you can work with one file and all of its subsets at the same time.  The idea of alternating forms provides for a greater level of security, for example, if a user needed to update an address field, they would not be able to access any fields which displayed confidential information.  The field in need of updating would only display the necessary or relevant information.
Menus are once again present and used as a guide.  The use of function keys allows the user to move about screens or forms quite easily.  Menus are also used for transferring information, either for

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data base 2nd

with the confidence of knowing that it is accessing up to date and exclusive information.



Some early DBMS=s consisted of:
 Condor 3
dBaseIII
Knowledgeman
Omnifile
Please
Power-Base
R-Base 4000
Condor 3, dBaseIII, and Omnifile will be examined more closely.

Condor 3
Is a relational database management system that evolved in the microcomputer environment since 1977.  Condor provides multi-file, menu-driven relational capabilities and a flexible command language.  By using a word processor, due to the absence of a text editor, frequently used commands can automated.
Condor 3 is an application development tool for multiple-file databases.  Although it lacks some of the capabilities like procedure repetition, it makes up for it with its ease to use and quick decent speed.
Condor 3 utilizes the advantages of menu-driven design.  Its portability enables it to import and export data files in five different ASCII formats.  Defining file structures is a relatively straightforward method by typing the field names and their length, the main part of designing the structure is about complete.  Condor uses six data types:

alphabetic
alphanumeric
C. numeric
C. decimal numeric
C. Julian date
C. dollar
Once the fields have been designed, data entry is as easy as pressing enter and inputting the respective values to the appropriate fields and like the newer databases, Condor too can use the Update, Delete, Insert, and Backspace commands.  Accessing data is done by creating an index.  The index can be used to perform sorts and arithmetic.

dBaseIII
DbaseIII is a relational DBMS which was partially built on dbaseII.  Like Condor 3, dbaseIII is menu-driven and has its menus built in several levels.  One of the problems discovered, was that higher level commands were not included in all menu levels.  That is, dBaseIII is limited to only basic commands and anything above that is not supported.
Many of the basic capabilities are easy to use, but like Condor, dBaseIII has inconsistencies and inefficiency.  The keys used to move and select items in specific menus are not always consistent through out.  If you mark an item to be selected from a list, once it=s marked it can not be

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Brief History Of Data Bases

Brief History Of Data Bases

In the 1960's, the use of main frame computers became widespread in many companies.  To access vast amounts of stored information, these companies started to use computer programs like COBOL and FORTRAN.  Data accessibility and data sharing soon became an important feature because of the large amount of information recquired by different departments within certain companies.  With this system, each application owns its own data files.  The problems thus associated with this type of file processing  was uncontrolled redundancy, inconsistent data, inflexibility, poor enforcement of standards, and low programmer maintenance.
In 1964, MIS (Management Information Systems) was introduced.  This would prove to be very influential towards future designs of computer systems and the methods they will use in manipulating data.
In 1966, Philip Kotler had the first description of how managers could benefit from the powerful capabilities of the electronic computer as a management tool.
In 1969, Berson developed a marketing information system for marketing research.  In 1970,  the Montgomery urban model was developed stressing the quantitative aspect of management by highlighting a data bank, a model bank, and a measurement statistics bank.  All of these factors will be influential on future models of storing data in a pool.
According to Martine, in 1981, a database is a shared collection of interrelated data designed to meet the needs of multiple types of end users.  The data is stored in one location so that they are independent of the programs that use them, keeping in mind data integrity with respect to the approaches to adding new data, modifying data, and retrieving existing data.  A database is shared and perceived differently by multiple users.  This leads to the arrival of Database Management Systems.
These systems first appeared around the 1970=s as solutions to problems associated with mainframe computers.  Originally, pre-database programs accessed their own data files.  Consequently, similar data had to be stored in other areas where that certain piece of information was relevant.  Simple things like addresses were stored in customer information files, accounts receivable records, and so on.  This created redundancy and inefficiency.  Updating files, like storing files, was also a problem.  When a customer=s address changed, all the fields where that customer=s address was stored had to be changed.  If a field happened to be missed, then an inconsistency was created.  When requests to develop new ways to manipulate and summarize data arose, it only added to the problem of having files attached to specific applications.  New system design had to be done, including new programs and new data file storage methods.  The close connection between data files and programs sent the costs for storage and maintenance soaring.  This combined with an inflexible method of the kinds of data that could be extracted, arose the need to design an effective and efficient system.
Here is where Database Management Systems helped restore order to a system of inefficiency.  Instead of having separate files for each program, one single collection of information was kept, a database.  Now, many programs, known as a database manager, could access one database

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2nd chapter

-and perhaps reduce the amount of keystrokes necessary in order to enter the year to date-most
IS groups have allocated two digits to represent the year. For example, "1996" is stored as "96"

in data files and "2000" will be stored as "00." These two-digit dates will be on millions of files
used as input for millions of applications. This two digit date affects data manipulation,
primarily subtractions and comparisons. (Jager, p. 1) For instance, I was born in 1957. If I ask
the computer to calculate how old I am today, it subtracts 57 from 96 and announces that I'm 39.
So far so good. In the year 2000 however, the computer will subtract 57 from 00 and say that I
am -57 years old. This error will affect any calculation that produces or uses time spans, such as
an interest calculation. Banker's beware!!!
Bringing the problem closer to the home-front, let's examine how the CAPS system is
going to be affected. As CAPS is a multifaceted system, I will focus on one area in particular,
ISIS. ISIS (Integrated Student Information System) has the ability to admit students, register
them, bill them, and maintain an academic history of each student (grades, transcripts, transfer
information, etc.) inside of one system. This student information system has hundreds and
hundreds of references to dates within it's OS. This is a COBOL system accessing a ADABAS
database. ADABAS is the file and file access method used by ISIS to store student records on
and retrieve them from. (Shufelt, p.1) ADABAS has a set of rules for setting up keys to specify
which record to access and what type of action (read, write, delete) is to be performed. The
dates will have to have centuries appended to them in order to remain correct. Their (CAPS)
"fix" is to change the code in the Procedure Division (using 30 as the cutoff >30 century = "19"
<30 century = "20"). In other words, if the year in question is greater than 30 (>30) then it can
be assumed that you are referring to a year in the 20th century and a "19" will be moved to the
century field. If the year is less than 30 (<30) then it will move a "20" to the century field. If absolutely necessary, ISIS will add a field and a superdescriptor index in order to keep record retrieval in the order that the program code expects. The current compiler at CAPS will not work beyond the year 2000 and will have to be replaced. The "temporary fix" (Kludge) just discussed (<30 or >30) will allow ISIS to operate until the year 2030, when they hope to have
replaced the current system by then.

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