An entity is basically the person place thing or

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Anentityis basically the person, place, thing, or event on which you maintain information. Eachcharacteristic or quality describing an entity is called anattribute. In the table below, eachcolumn describes a characteristic (attribute) of John Jones’ (who is theentity) address.First NameLast NameStreetCityStateZipTelephoneJohnJones111 MainStCenter CityOhio22334555-123-6666Suppose you decide to create a database for your newspaper delivery business. In order tosucceed, you need to keep accurate, useful information for each of your customers. You set up adatabase to maintain the information. For each customer, you create a record. Within each recordyou have the following fields: customer first name, customer last name, street address, city, state,zip, ID, and date last paid. Smith, Jones, and Brooks are the records within a file you decide tocall Paper Delivery. The entities then are Smith, Jones, and Brooks, the people about whom youare maintaining information. The attributes are customer’s name (first and last), address (street,city, state, zip code), ID, and date last paid. This is a very simplistic example of a database, but itshould help you understand the terminology.Problem with the traditional file environmentBuilding and maintaining separate databases within an organization is usually the main cause of“islands of information.” It may begin in all innocence, but it can quickly grow to monstrousproportions. Let’s look at some of the problems traditional file environments have caused.Data Redundancy and Inconsistency:Have you ever gotten two pieces of mail from the sameorganization? For instance, you get two promotional flyers from your friendly neighborhoodgrocery store every month. It may not necessarily be that you’re a popular person. It’s probablybecause your data was somehow entered twice into the business’s database. That’sdataredundancy.Now, let’s say you change residences and, consequently, your address. You notifyevery one of your new address including your local bank. Everything is going smoothly withyour monthly statements. All of a sudden, at the end of the year, the bank sends a Christmas cardto your new address and one to your old address. Why? Because your new address was changedin one database, but the bank maintains a separate database for its Christmas card list and youraddress was never changed in it. That’sdata inconsistency.Just from these two simple examplesyou can see how data redundancy and inconsistency can waste resources and cause nightmareson a much larger scale.Program-Data Dependence:Some computer software programs, mainly those written for large,mainframe computers, require data to be constructed in a particular way. Because the data arespecific to that program, it can’t be used in a different program. If an organization wants to usethe same data in a different program, it has to reconstruct it. Now the organization is spending9 |P a g e

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Term
Fall
Professor
NoProfessor
Tags
Data Management, Data Mining, Database management system

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