Question

我有一个看起来像这样的表：

timestamp | commodity | amount | price |

我试图得到商品的加权平均值，从过去7天开始每天（为了创建图表，c＃程序），我设法创建一个查询来获得加权平均值：

SELECT SUM(price * amount),
       SUM(amount) 
  FROM [table_name] 
 WHERE (commodity = @commodity) 
   AND (timestamp >= @fromDate 
   AND timestamp <= @toDate);

所以，我发送此查询7次，每次都将（-1）添加到fromDate和toDate，以获得过去7天的平均值。

我想询问是否有办法在1个查询中执行此操作，如果存在，是否可以实现以获取上个月的相同信息。

Answer 1

您可以使用转换为日期并执行以下代码：

  SELECT convert(date, timestamp) as [Dates], 
         SUM(price * amount),
         SUM(amount) 
    FROM [table_name] 
   WHERE (commodity = @commodity) 
     AND (timestamp >= @fromDate 
     AND timestamp <= @toDate)
GROUP BY convert(date, timestamp)

Answer 2

你必须按日期分组

 SELECT SUM(price* amount),SUM(amount) FROM [table_name] WHERE (commodity = @commodity) AND (cast(timestamp  as date)>= @fromDate AND cast(timestamp  as date)<= @toDate)
Group By cast(timestamp  as date)

Answer 3

您应该按日期对数据进行分组：

SELECT SUM(price * amount),SUM(amount) 
FROM [table_name] 
WHERE (commodity = @commodity) 
AND (timestamp >= @fromDate 
AND timestamp <= @toDate)
GROUP BY CAST(timestamp as DATE);

Answer 4

要生成日期，您可以按如下方式使用：

;with Datescte as (
      Select top (datediff(day, @fromDate, @toDate) +1) Dt = Dateadd(day, Row_Number() over (order by (Select null))-1, @fromDate) 
        from master..spt_values s1, master..spt_values s2
    ), cte2 as (
      SELECT convert(date, timestamp) as [Dates], 
             SUM(price * amount) as [Sum_Price_Amount],
             SUM(amount) as [Sum_Amount] 
        FROM [table_name] 
       WHERE (commodity = @commodity) 
         AND (timestamp >= @fromDate 
         AND timestamp <= @toDate)
    GROUP BY convert(date, timestamp)
    )
      Select Dt as [Dates] , Sum_Price_Amount, Sum_Amount 
        FROM Datescte d
        LEFT JOIN cte2 d2
          ON d.Dt = d2.Dates

SQL - 获取过去7天的平均价格

4 个答案: