Avg Incidents Per Customer by Month | Dataford Interview Questions

Write a SQL query to calculate the average number of security incidents per customer by month. Use the customers and security_incidents tables. Include every customer in the monthly average, including customers with no incidents during that month. Ignore incidents without a valid customer or incident date.

Output

One row per month represented by a dated incident.
Columns: month, formatted as YYYY-MM, and avg_incidents_per_customer.
Round the average to two decimal places and order chronologically by month.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(150)	Customer organization name
service_tier	VARCHAR(30)	Cloud Security Services subscription tier

security_incidents

Column	Type	Description
incident_idPK	INT	Unique security incident identifier
customer_id	INT	Customer associated with the incident
incident_date	TIMESTAMP	Timestamp when the incident was recorded
incident_type	VARCHAR(50)	Security incident classification
severity	VARCHAR(20)	Incident severity level

Your question is Avg Incidents Per Customer by Month. 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