Running Totals With SQL Window Functions | Dataford Interview Questions

Your question is Running Totals With SQL Window Functions. Start with the requirements and the two tables on the right.

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Problem

Munich Re needs a regional view of policy claims for portfolio monitoring. Write a PostgreSQL query that calculates monthly eligible claims and a rolling twelve-month total for each region.

Requirements

Join policies to claims using the policy identifier.
Include only claims with a status of Paid or Approved, and exclude policies without a region.
Aggregate eligible claim amounts by region and calendar month.
Use a window function to calculate the total for the current month and the preceding eleven months. Return the results ordered by region and month.

Schema

policies

Column	Type	Description
policy_idPK	INTEGER	Unique policy identifier
policy_number	VARCHAR(20)	Munich Re policy reference
region	VARCHAR(40)	Geographic region assigned to the policy
inception_date	DATE	Policy start date

claims

Column	Type	Description
claim_idPK	INTEGER	Unique claim identifier
policy_id	INTEGER	Identifier of the related policy
claim_date	DATE	Date the claim was recorded
claim_amount	NUMERIC(12,2)	Claim amount in euros
claim_status	VARCHAR(20)	Current processing status of the claim