Finding Duplicate Records | Dataford Interview Questions

Bismart's customer master table may contain repeated email addresses from multiple imports. Write a SQL query to identify duplicate email values in the customers table.

Requirements

Return each email that appears more than once.
Include the number of rows for each duplicate email.
Sort the result by duplicate count descending, then by email ascending.

Schema

customers

Column	Type	Description
customer_idPK	INT	Primary key for each customer record
full_name	VARCHAR(100)	Customer name
email	VARCHAR(255)	Customer email address, may contain duplicates or NULL
created_at	DATE	Record creation date

Your question is Finding Duplicate Records. Start with the requirements and the one table 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

Bismart's customer master table may contain repeated email addresses from multiple imports. Write a SQL query to identify duplicate email values in the customers table.

Requirements

Return each email that appears more than once.
Include the number of rows for each duplicate email.
Sort the result by duplicate count descending, then by email ascending.

Schema

customers

Column	Type	Description
customer_idPK	INT	Primary key for each customer record
full_name	VARCHAR(100)	Customer name
email	VARCHAR(255)	Customer email address, may contain duplicates or NULL
created_at	DATE	Record creation date

Your question is Finding Duplicate Records. Start with the requirements and the one table 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.