Question

SELECT date_trunc('month', dateordered), SUM(orders) - (
SELECT SUM(orders)
FROM c_orders
WHERE orderstatus = 'returned'
)
FROM c_orders
WHERE orderstatus = 'complete'
GROUP BY 1

这给了我以下输出：

date_trunc  total_orders
2016-08-01 00:00:00 129
2016-09-01 00:00:00 125
2016-10-01 00:00:00 160
2016-11-01 00:00:00 202
2016-12-01 00:00:00 357

我想从八月开始计算逐月变化的百分比。我怎么能在我的SQL查询中做到这一点？

TIA

Answer 1

为什么使用该查询？这更简单：

SELECT date_trunc('month', dateordered) as yyyymm,
       SUM(CASE WHEN orderstatus = 'returned' THEN orders
                WHEN orderstatus = 'complete' THEN - orders
                ELSE 0
            END) as net
FROM c_orders
GROUP BY yyyymm
ORDER BY yyyymm;

然后使用lag()：

轻松回答您的问题

WITH o as (
      SELECT date_trunc('month', dateordered) as yyyymm,
             SUM(CASE WHEN orderstatus = 'returned' THEN orders
                      WHEN orderstatus = 'complete' THEN - orders
                      ELSE 0
                  END) as net
      FROM c_orders o
      GROUP BY yyyymm
     )
SELECT o.*, 
       (net / LAG(net) OVER (ORDER BY yyyymm) - 1) as net_change
FROM o
ORDER BY yyyymm;

要获取2016-08以来的数据，您需要更多级别的子查询：

SELECT o.*
FROM (SELECT o.*, 
             (net / LAG(net) OVER (ORDER BY yyyymm) - 1) as net_change
      FROM o
     ) o
WHERE yyyymm >= '2016-08-01'
ORDER BY yyyymm;

Answer 2

您可以使用LAG()从上一行中选择total_orders进行百分比计算

with total_orders(date_trunc,total_orders) as (
  values
('2016-08-01 00:00:00' ,129)
,('2016-09-01 00:00:00' ,125)
,('2016-10-01 00:00:00' ,160)
,('2016-11-01 00:00:00' ,202)
,('2016-12-01 00:00:00' ,357)    
)
,with_base as (select *,(lag(total_orders,1,0) over (ORDER BY date_trunc))
from total_orders)
select  date_trunc
      , total_orders
      , (case when 0 = lag 
              then 0 
              else total_orders / lag::FLOAT  * 100 end)::INT as percent 
from with_base;

结果：

date_trunc            total_orders  percent
"2016-08-01 00:00:00",129          ,0
"2016-09-01 00:00:00",125          ,97
"2016-10-01 00:00:00",160          ,128
"2016-11-01 00:00:00",202          ,126
"2016-12-01 00:00:00",357          ,177

计算SQL中的月度增长百分比

2 个答案: