如何在 SQL 中制作百分比列？

Question

这里是 SQL 的超级新手！

我正在尝试在此处创建第三列，其中包含重新交付的订单与总订单的百分比，但我不知道该怎么做（即输出的第一行的值应为 4%）

这是我的代码：

SELECT DISTINCT WH AS Warehouse,
                count(order_id) AS Orders,
                sum(CASE
                        WHEN is_redelivered=1 THEN 1
                        ELSE 0
                    END) AS Redelivered
FROM
  (SELECT DISTINCT o.id AS order_id,
                   wh.code AS WH,
                   o.initial_delivery_date,
                   date(o.delivered_by) AS delivered_by,
                   if(o.delivered_by>o.initial_delivery_date, 1, 0) AS is_redelivered
   FROM `order` o
   JOIN `order_status` os ON o.id = os.id
   JOIN `warehouse` wh ON o.warehouse_id = wh.id
   WHERE o.created_at BETWEEN '2020-11-22' AND '2020-11-28'
     AND os.status != 'Cancelled') orders
GROUP BY WH

Here's the current output

Answer 1

如果我没看错的话，你可以这样做：

select 
    wh.code as wh, 
    count(*) as cnt_orders,
    sum(o.delivered_by > o.initial_delivery_date) as cnt_redelivered
    100 * avg(o.delivered_by > o.initial_delivery_date) as percent_redelivered
from `order` o
join `order_status` os on o.id = os.id
join `warehouse` wh on o.warehouse_id = wh.id
where o.created_at between '2020-11-22' and '2020-11-28' and os.status <> 'cancelled'
group by wh.id, wh.code

如何在 SQL 中制作百分比列？

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