Chapter 13Chapter 13Database Design for Student Loan Limited
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Outline Outline
Case descriptionConceptual data modelingLogical database designPhysical database design
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Case OverviewCase Overview
Guaranteed Student LoansEnvironment
– Student– Lender– Service Provider– Guarantor– Department of Education
Replace existing information system
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Loan Processing WorkflowLoan Processing Workflow
Apply
Approveloan
Originateloan Separate from
school
Sendbill
Makepayment
Misspayments
Claim
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Major DocumentsMajor Documents
Loan origination formDisclosure letterStatement of accountLoan activity report
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Loan Origination ERDLoan Origination ERDStudent
StdNo
Loan
LoanNo
Lender
LenderNo
Guarantor
GuarantorNo
Institution
InstitutionNo
DisburseLine
DateLoanNo
GivenTo
AuthorizesGuarantees
Uses
Sent
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Disclosure Letter StructureDisclosure Letter Structure
Parent NodeLoanNo, DateSentStdName, RepayDate,AmtBorrowed, NumPayments,IntRate, EstFinChargeFirstPayDate, MonthPayment,LastPayDate
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Disclosure Letter ERDDisclosure Letter ERDStudent
StdNo
Loan
LoanNo
Lender
LenderNo
Guarantor
GuarantorNo
Institution
InstitutionNo
DisburseLine
DateLoanNo
GivenTo
Authorizes
Guarantees
Uses
Sent
DiscLetter
LetterNoIncludes
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Statement StructureStatement StructureParent Node
StatementNoDate, StudentNo,Name, Address, City, StateZip, DueDate, AmountEnclosed,PayMethod, AmountDue
Child NodeLoanNoBalance
Rate
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Loan Activity StructureLoan Activity Structure
Parent NodeStudentNo
Date, Name, Address, City,State, Zip
Child NodeLoanNo
BegBalance, EndBalance,Principal, Interest
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
Schema Conversion RulesSchema Conversion Rules
Entity type rule1-M relationship ruleM-N relationship ruleIdentification dependency rule
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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)
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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
McGraw-Hill/Irwin © 2004 The McGraw-Hill Companies, Inc. All rights reserved.
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.