SQL Email Null Handling | Dataford Interview Questions

Alcon is reviewing the completeness of contact records used for customer communications. Given the t1 table, write a PostgreSQL query that calculates what percentage of records contain an email address.

Treat an email address as present when email is non-null. The result should be safe against division by zero and should report the percentage rounded to two decimal places.

Requirements

Return the total number of records and the number of records with non-null email addresses.
Calculate the email coverage percentage as records_with_email / total_records * 100.
Round the percentage to two decimal places and avoid integer division or division-by-zero errors.

Schema

Column	Type	Description
name	VARCHAR(100)	Alcon contact name
email	VARCHAR(255)	Contact email address

Your question is SQL Email Null Handling. 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

Treat an email address as present when email is non-null. The result should be safe against division by zero and should report the percentage rounded to two decimal places.

Requirements

Return the total number of records and the number of records with non-null email addresses.
Calculate the email coverage percentage as records_with_email / total_records * 100.
Round the percentage to two decimal places and avoid integer division or division-by-zero errors.

Schema

Column	Type	Description
name	VARCHAR(100)	Alcon contact name
email	VARCHAR(255)	Contact email address

Your question is SQL Email Null Handling. 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.