SQL: Deduplicate Latest Records

MediumSQL · PostgreSQL00:00

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Your question is SQL: Deduplicate Latest Records. Start with the requirements and the one table on the right.

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Problem

Write a SQL query to find duplicate records in a customer table and keep only the latest record per customer. Use the customer_records table, treating the greatest updated_at value as latest. If timestamps tie, retain the row with the greatest record_id.

Output

Return one row per customer with record_id, customer_id, customer_name, email, updated_at, and duplicate_count.
Include customers with and without duplicates, excluding superseded records.
Order by customer_id ascending.

Schema

customer_records

Column	Type	Description
record_idPK	INT	Unique identifier for the stored customer record
customer_id	INT	Business identifier shared by records for the same customer
customer_name	VARCHAR(150)	Customer's full name
email	VARCHAR(255)	Customer email address
updated_at	TIMESTAMPTZ	Timestamp when the customer record was last updated

Tablescustomer_records

Your solutionPostgreSQL

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