Chapter 13Chapter 13Database Design for Student Loan Limited

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Outline Outline

Case descriptionConceptual data modelingLogical database designPhysical database design

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Case OverviewCase Overview

Guaranteed Student LoansEnvironment

– Student– Lender– Service Provider– Guarantor– Department of Education

Replace existing information system

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Loan Processing WorkflowLoan Processing Workflow

Apply

Approveloan

Originateloan Separate from

school

Sendbill

Makepayment

Misspayments

Claim

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Major DocumentsMajor Documents

Loan origination formDisclosure letterStatement of accountLoan activity report

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Loan Origination FormLoan 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

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Loan Origination ERDLoan Origination ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNo

Guarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

AuthorizesGuarantees

Uses

Sent

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Disclosure Letter StructureDisclosure Letter Structure

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

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Disclosure Letter ERDDisclosure Letter ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNo

Guarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

Authorizes

Guarantees

Uses

Sent

DiscLetter

LetterNoIncludes

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Statement StructureStatement StructureParent Node

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

Child NodeLoanNoBalance

Rate

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Statement ERDStatement ERDStudent

StdNo

Loan

LoanNo

Lender

LenderNoGuarantor

GuarantorNo

Institution

InstitutionNo

DisburseLine

DateLoanNo

GivenTo

AuthorizesGuarantees

Uses

Sent

DiscLetter

LetterNo

Includes

Statement

StatementNo

StatementLoan

StatementNoLoanNo

AppliedTo

StatementsApplied

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Loan Activity StructureLoan Activity Structure

Parent NodeStudentNo

Date, Name, Address, City,State, Zip

Child NodeLoanNo

BegBalance, EndBalance,Principal, Interest

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Loan Activity ERDLoan 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

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Schema Conversion RulesSchema Conversion Rules

Entity type rule1-M relationship ruleM-N relationship ruleIdentification dependency rule

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Schema Conversion ResultSchema 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

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NormalizationNormalization

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

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Normalized Table DesignNormalized 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

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Physical Database DesignPhysical 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 denomalizationOther implementation considerations

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Application ProfilesApplication 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

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Application FrequenciesApplication 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

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Table ProfilesTable 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)

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Index SelectionsIndex 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

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Derived Data and Derived Data and Denormalization DecisionsDenormalization DecisionsDerived 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

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Other Implementation IssuesOther 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

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Application Development NotesApplication 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

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SummarySummary

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.