How to Get First and Last Values in Each Group in SQL?

SELECT customer_id, MIN(order_date) AS first_order, MAX(order_date) AS last_order FROM orders GROUP BY customer_id;

This SQL query retrieves the first and last order dates for each customer by grouping the orders.

1. SELECT the customer_id and aggregate functions for first and last orders.
2. Use MIN() to find the earliest order date and MAX() for the latest.
3. FROM the orders table to specify the data source.
4. GROUP BY customer_id to ensure results are grouped per customer.

• Customers with only one order will show the same date for first and last.
• If there are no orders for a customer, they will not appear in the results.
• Handling NULL values in order_date may affect the output.
• Multiple orders on the same date will return that date for both first and last.