SQL Total Orders by Client Type | Dataford Interview Questions

PenFed Credit Union's marketing analytics team needs to compare order activity from new and existing clients during January 2025. A client is new if January contains their first recorded order, and existing if they placed an order before January 2025.

Write a PostgreSQL query that calculates the total number of January 2025 orders for each client type.

Requirements

Determine each client's first recorded order date.
Include only orders from 2025-01-01 through 2025-01-31, using an exclusive upper date boundary.
Classify each included order as new or existing with CASE and return both categories, including a zero count if a category has no orders.
Return client_type and total_orders, ordered with new before existing.

Schema

clients

Column	Type	Description
client_idPK	INT	Unique PenFed client identifier
client_name	VARCHAR(100)	Client's display name

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
client_id	INT	References clients.client_id
order_date	DATE	Date the order was placed

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