3_Lecture_Notes

3_Lecture_Notes - MIS 380 CLASS 3 What We Are Covering...

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1 CLASS # 3 MIS 380 Quiz 1 – Readings 1 & 2, Relational Model, PKs Normalization Step 1: Create an un-normalized relation Step 2: Separate repeating & non-repeating attributes Step 3: Remove partial dependencies Step 4: Remove transitive dependencies Normal forms (1NF, 2NF, and 3NF) Normalizing additional forms Step 5: Merge relations Using Normalization to Check ERDs Assignment 2 – Patient Database Normalization What We Are Covering Today
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2 CLASS # 3 MIS 380 NORMALIZATION IN THE RELATIONAL MODEL WE NEED TABLES THAT ALLOW US TO : INTERRELATE DATA MAINTAIN DATA CONSISTENCY MINIMIZE REDUNDANCY THE NORMALIZATION PROCESS CAN BE USED TO CONVERT EXISTING FORMS AND REPORTS INTO A RELATIONAL MODEL FOR A DATABASE ALSO USEFUL FOR CHECKING THE CONVERSION PROCESS OF GOING FROM AN ERD TO RELATIONAL TABLES GOAL: THIRD NORMAL FORM (3NF) - EACH NON-KEY COLUMN DEPENDS ON THE KEY, THE WHOLE KEY, AND NOTHING BUT THE KEY
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3 CLASS # 3 MIS 380 ACME CORPORATION 125 MAIN ST. CUSTOMER ORDER FORM ORDER: 1234 CUSTOMER: H36475 DATE: 01/01/90 NAME: FRED JONES SALESPERSON: 123 CODE DESCRIPTION PRICE QNTY X-234 RADIO 29.95 2 X-334 RADIO 39.95 1 G-484 TELEPHONE 59.00 1 R-586 CLOCK 15.25 3 NORMALIZATION BEGINS BY TAKING A FORM OR REPORT REPRESENTING DATA THE COMPANY WANTS TO STORE
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4 CLASS # 3 MIS 380 STEP 1 - CREATE AN UN-NORMALIZED RELATION DETERMINE ATTRIBUTES CHOOSE AND UNDERLINE PRIMARY KEY INDICATE ANY REPEATING ATTRIBUTES UN-NORMALIZED RELATION OrderId CustomerId OrderDate CustomerName SalesPersonId ProductCode Description Price Quantity REPEATING O# C# DATE NAME SMAN P# DESC PRICE QUAN 1234 X X X X X X X X X X X X X X X X 1235 X X X X X X X X X X X X NOTE THAT THIS TABLE IS NOT A VALID RELATION SINCE SOME OF THE CELLS WOULD CONTAIN MORE THAN ONE PIECE OF DATA RELATED ATTRIBUTES THAT CAN HAVE MULTIPLE VALUES IN A SINGLE ROW ACME CORPORATION 125 MAIN ST. CUSTOMER ORDER FORM ORDER: 1234 CUSTOMER: H36475 DATE: 01/01/90 NAME: FRED JONES SALESPERSON: 123 CODE DESCRIPTION PRICE QNTY X-234 RADIO 29.95 2 X-334 RADIO 39.95 1 G-484 TELEPHONE 59.00 1 R-586 CLOCK 15.25 3 Not Attributes Primary Key
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5 CLASS # 3 MIS 380 THINK ABOUT IT UN-NORMALIZED RELATION OrderId CustomerId OrderDate CustomerName SalesPersonId ProductCode Description Price Quantity REPEATING The mixing of repeating and non-repeating items on the same form is an indication that there are at least two different entities represented on the form – one for the repeating items and one for the non-repeating Here we have an order entity represented by the non-repeating items and a product entity represented by the repeating items. What is the relationship between orders and products? The form shows directly that a single order contains many products. But on how many orders can a particular product appear? This form shows just one order but there will be many such forms and across those various orders a particular product can appear on many orders.
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This note was uploaded on 01/24/2011 for the course FIA 111 taught by Professor Matta during the Spring '10 term at Hocking.

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3_Lecture_Notes - MIS 380 CLASS 3 What We Are Covering...

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