lec11 - Normalization Chapter 19(Overview EECS 484 Database...

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1 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 1 Normalization Chapter 19 (Overview) 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 2 Logical Database Design Revisited Requirements Analysis Conceptual Design Logical DB Design Schema Normalization Fix mistakes in initial design Functional Dependencies and Normal Forms provide deeper understanding of schema (Favorite topic of interviewers)
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2 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 3 Recall the Redundancy Problem What is a good relational schema? Suppose we put this all in one table… Student Course Enroll grade desc unique name addr cid C painting Art_400 A2 Alice A database EECS_484 Ypsi Bob Art_400 EECS_376 EECS_484 C id B painting Ypsi Bob A theory A2 Alice B database A2 Alice Grade Desc Addr U niquen ame Redundancy problems: Course information stored once per student signed up Student information stored once per course the student is taking Many-to -Many 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 4 Recall the Redundancy Problem Problem 1: Redundant Storage Store course info once per student enrolled… Problem 2: Update Anomalies What if we want to change a student’s address? Problem 3: Insert Anomalies Insert a new course… But what if that course doesn’t have any students signed up yet? Problem 4: Delete Anomalies What if we want to delete Alice? C painting Art_400 A2 Alice A database EECS_484 Ypsi Bob Art_400 EECS_376 EECS_484 C id B painting Ypsi Bob A theory A2 Alice B database A2 Alice Grade Desc Addr Unique n ame
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3 2/13/11 EECS 484: Database Management Systems, Kristen LeFevre 5 Recall the Redundancy Problem Ypsi Bob A2 Alice Addr Unique n ame painting Art_400 EECS_376 EECS_484 C id theory database Desc B A C A B Grade Art_400 Alice EECS_484 Bob Art_400 EECS_376 EECS_484 C id Bob Alice Alice U niquen ame Students Enroll Courses A better schema… How does this resolve… Redundant storage? Update anomalies?
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lec11 - Normalization Chapter 19(Overview EECS 484 Database...

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