Top Customers Last 30 Days | Dataford Interview Questions

Write a SQL query to find the top 5 customers with the highest total transaction value in the last 30 days.

Use PostgreSQL syntax and treat the period as transaction dates from CURRENT_DATE - INTERVAL '30 days' through today.

Output

One row per customer, with customer_id, customer_name, and total_transaction_value.
Include only the five highest totals, ordered from highest to lowest.
Break ties by ascending customer_id.

customers

Column	Type	Description
customer_idPK	INT	Unique Ally Financial customer identifier
customer_name	VARCHAR(100)	Customer display name

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
customer_id	INT	Customer associated with the transaction
transaction_date	DATE	Transaction posting date
transaction_value	NUMERIC(12,2)	Transaction amount in dollars

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