如何在SQL上选择第一行和最后一行的值？

-- 选择最早的订单
SELECT order_id, order_date
FROM (
    SELECT order_id, order_date,
           ROW_NUMBER() OVER (ORDER BY order_date ASC) as rn
    FROM orders
) t
WHERE rn = 1;

-- 选择最晚的订单
SELECT order_id, order_date
FROM (
    SELECT order_id, order_date,
           ROW_NUMBER() OVER (ORDER BY order_date DESC) as rn
    FROM orders
) t
WHERE rn = 1;

-- 选择最早的订单
SELECT order_id, order_date
FROM orders
ORDER BY order_date ASC
LIMIT 1;

-- 选择最晚的订单
SELECT order_id, order_date
FROM orders
ORDER BY order_date DESC
LIMIT 1;

-- 选择最早的订单日期
SELECT MIN(order_date) as first_order_date
FROM orders;

-- 选择最晚的订单日期
SELECT MAX(order_date) as last_order_date
FROM orders;