平均首单客单价sql输出结果保留一位小数的sql

好的，以下是平均首单客单价输出结果保留一位小数的SQL语句：

SELECT
  ROUND(AVG(order_amount - discount), 1) AS avg_order_amount, 
  ROUND(SUM(ad_cost) / COUNT(DISTINCT user_id), 1) AS avg_ad_cost
FROM
(
  SELECT
    a.user_id,
    a.order_id,
    a.order_amount,
    (SELECT SUM(price * quantity) FROM order_detail WHERE order_id = a.order_id) AS goods_amount,
    (SELECT SUM(ad_cost) FROM ad_record WHERE user_id = a.user_id AND ad_date >= '2021-10-01' AND ad_date <= '2021-10-31' AND ad_type = 'ACQUISITION') AS ad_cost,
    (SELECT SUM(price * quantity) FROM order_detail WHERE order_id = a.order_id) - a.order_amount AS discount
  FROM
    orders a
  WHERE
    a.user_id IN (102, 101, 104) AND
    a.order_date >= '2021-10-01' AND a.order_date <= '2021-10-31'
) tmp;

在SELECT语句中，将AVG函数和ROUND函数一起使用，指定保留1位小数，即可输出平均首单客单价结果保留一位小数的查询结果。