Chapter 13

McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

Chapter 13

Database Design for Student Loan Limited

13-2

Outline Case description Conceptual data modeling Logical database design Physical database design

13-3

Case Overview Guaranteed Student Loans Environment

Student Lender Service Provider Guarantor Department of Education

Replace existing information system

13-4

Loan Processing Workflow

Apply

Approveloan

Originateloan Separate from

school

Sendbill

Makepayment

Misspayments

Claim

13-5

Major Documents Loan origination form Disclosure letter Statement of account Loan activity report

13-6

Loan Origination FormParent Node

LoanNoProcDate, DisbMeth, DisbBank,RouteNo, AcctNo, DateAuthNoteValue, Subsidized, Rate, StdNoName, Address, City, StateZip, DOB, ExpGradMonth,ExpGradYear, Phone, GuarantorNo,Guarantor, Name, LenderNo, LenderName, InstID, Institution Name,Address, City, State, Zip

Child NodeDate

AmountOrigFeeGuarFee

13-7

Loan Origination ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNo

Guarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

AuthorizesGuarantees

Uses

Sent

13-8

Disclosure Letter Structure

Parent NodeLoanNo, DateSentStdName, RepayDate,AmtBorrowed, NumPayments,IntRate, EstFinChargeFirstPayDate, MonthPayment,LastPayDate

13-9

Disclosure Letter ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNo

Guarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

Authorizes

Guarantees

Uses

Sent

DiscLetter

LetterNoIncludes

13-10

Statement StructureParent Node

StatementNoDate, StudentNo,Name, Address, City, StateZip, DueDate, AmountEnclosed,PayMethod, AmountDue

Child NodeLoanNoBalance

Rate

13-11

Statement ERD

Student

StdNo

Loan

LoanNo

Lender

LenderNoGuarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

AuthorizesGuarantees

Uses

Sent

DiscLetter

LetterNo

Includes

Statement

StatementNo

StatementLoan

StatementNoLoanNo

AppliedTo

StatementsApplied

13-12

Loan Activity Structure

Parent NodeStudentNo

Date, Name, Address, City,State, Zip

Child NodeLoanNo

BegBalance, EndBalance,Principal, Interest

13-13

Loan Activity ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNoGuarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

AuthorizesGuarantees

Uses

Sent

DiscLetter

LetterNo

Includes

Statement

StatementNo

StatementLoan

StatementNoLoanNo

AppliedTo

StatementsApplied

LoanActivity

ReportNoMailedTo

13-14

Schema Conversion Rules Entity type rule 1-M relationship rule M-N relationship rule Identification dependency rule

13-15

Schema Conversion Result

StudentStdNo

StatementStatementNoStdNo

LoanActivityReportNoStdNo

DiscLetterLetterNoLoanNo

GuarantorGuarantorNo Lender

LenderNo

InstitutionInstID

DisburseLineDateSentLoanNo

AppliedStatementNoLoanNo

LoanLoanNoStdNo

GuarantorNoInstID

LenderNo

1

1

1

1

1

1

1

1

1

8

88 8

8

8

8

8

8

1

8

13-16

Normalization Student not in BCNF because of Zip FD

Zip State

Loan not in BCNF because of RouteNo FD RouteNo DisBank

Institution not in BCNF because of Zip FDs Zip City, State

13-17

Normalized Table Design

StudentStdNoZip

StatementStatementNo

StdNo

LoanActivityReportNoStdNo

DiscletterLetterNoLoanNo

GuarantorGuarantorNo Lender

LenderNo

BankRouteNo

DisburseLineDateSentLoanNo

AppliedStatementNoLoanNo

LoanLoanNoStdNo

GuarantorNoInstID

LenderNoRouteNo

1

1

1

1

11

1

1

1

8

88

88

8

8

8

8

1

8

InstitutionInstIDZip

ZipCodeZip

1

8

8 1

18

13-18

Physical Database Design Application profiles: tables, conditions,

parameter values, and frequencies Table profiles: estimated number of rows

and distribution of values Index selection: clustering and non

clustering indexes Derived data and denomalization Other implementation considerations

13-19

Application ProfilesApplication Tables Conditions

Verify data (for loan origination)

Student, Lender, Institution, Guarantor

StdNo = $X; LenderNo = $Y; InstID = $Z; GuarantorNo = $W

Create loan (for loan origination)

Loan, DisburseLine

1 row inserted in Loan; multiple rows inserted in DisburseLine

Create student (for loan origination)

Student 1 row inserted

13-20

Application FrequenciesApplication Frequency Comments

Verify data 100,000/year Most activity at beginning of term

Create loan 100,000/year Most activity at beginning of term

Create student 20,000/year Most students are repeat Create disclosure letter

50,000/year Spread evenly throughout year

Display disclosure letter

5,000/year Spread evenly throughout year

13-21

Table ProfilesTable Number

of Rows Column (Number of Unique Values)

Student 100,000 StdNo (PK), Name (99,000), Address (90,000), City(1,000), Zip (1,000), DOB (365), ExpGradMonth (12), ExpGradYear (10)

Loan 300,000 LoanNo (PK), ProcDate (350), DisbMethod (3), DisbBank (3,000), RouteNo (3,000), AcctNo (90,000), DateAuth (350), NoteValue (1,000), Subsidized (2), Rate (1,000), Balance (10,000), StdNo (100,000), InstID (2,000), GuarantorNo (100), LenderNo (2,000)

13-22

Index Selections

Column Index Kind Rule Student.StdNo Clustering 1 Student.Name Nonclustering 3 Statement.StatementNo Clustering 1 DiscLetter.LetterNo Clustering 1 Loan.LoanNo Clustering 1 Institution.InstID Clustering 1

13-23

Derived Data and Denormalization Decisions Derived data

Loan.NoteValue DiscLetter and LoanActivity tables have

derived data in the image columns.

Denormalization LenderNo and Lender.Name in the Loan table

violates BCNF, but it may reduce joins between the Loan and the Lender tables

13-24

Other Implementation Issues Processing volumes in a new system can

be much larger than in the old system Poor quality of old data may cause many

rejections in the conversion process Size of image data

13-25

Application Development Notes Provides cross check on quality of

database design Data requirements for forms and reports

Loan origination form Loan activity report

Derived data maintenance: AFTER ROW trigger for Loan.Balance

13-26

Summary Case includes a significant subset of

student loan processing. Solution depicts models for database

development phases. Next step: database development for a

real organization Open-ended, unclear, and changing

requirements are challenges.