SQL Retention for Repeat Borrowers | Dataford Interview Questions

Write a SQL query to find the monthly retention rate of borrowers who have taken out multiple loans with Upstart.

Use funded loans only. A borrower is retained for a month if they have another funded loan in the immediately following calendar month. Include only borrowers with at least two funded loans overall.

Output

One row per activity month with month_start, retained_borrowers, eligible_borrowers, and retention_rate
Include months containing eligible borrower activity, including months with zero retention
Calculate retention_rate as a percentage rounded to two decimal places
Sort by month_start ascending

Schema

borrowers

Column	Type	Description
borrower_idPK	INT	Unique Upstart borrower identifier
borrower_name	VARCHAR(100)	Borrower display name
email	VARCHAR(255)	Borrower email address

loans

Column	Type	Description
loan_idPK	INT	Unique loan identifier
borrower_id	INT	References borrowers.borrower_id
status	VARCHAR(20)	Loan lifecycle status
funded_at	DATE	Date the loan was funded
loan_amount	DECIMAL(12,2)	Original funded loan amount

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