Explain a SQL Query | Dataford Interview Questions

Tell me about a time you reviewed a SQL query and explained what was happening.

Review the SQL logic represented by the supplied schema and sample data. Explain the result, identify important correctness issues involving filtering, unmatched rows, NULL values, and classification, then provide a corrected PostgreSQL query.

Output

One row per active customer
Columns: customer_id, customer_name, claim_count, total_paid, and payment_band
Include active customers with no qualifying claims, exclude claims outside 2025, and sort by total_paid descending, then customer_id ascending

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer name
status	VARCHAR(20)	Customer status

claims

Column	Type	Description
claim_idPK	INT	Unique claim identifier
customer_id	INT	Customer associated with the claim
claim_type	VARCHAR(40)	Claim classification
service_date	DATE	Date services were provided
paid_amount	NUMERIC(12,2)	Amount paid for the claim

Your question is Explain a SQL Query. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem