Question

   SELECT 

        day,
        SUM(profit) AS TotalProfit,
        SUM(revenue) AS TotalRevenue,
        TotalProfit/TotalRevenue AS ProfitMargin

    FROM table

它表示 TotalProfit 未列为表格列。我想避免做SUM（利润）/ SUM（收入），因为真正的公式要复杂得多。

Answer 1

您无法在选择条款中引用别名。使用像sum

这样的聚合函数时，必须使用group by

选择

    day,
    SUM(profit) AS TotalProfit,
    SUM(revenue) AS TotalRevenue,
    SUM(profit)/SUM(revenue) AS ProfitMargin

FROM table

按天分组

Answer 2

再次这样做：

 SELECT 
        day,
        SUM(profit) AS TotalProfit,
        SUM(revenue) AS TotalRevenue,
        SUM(profit)/SUM(revenue) AS ProfitMargin

    FROM table
    GROUP BY Day

Answer 3

为了使用先前声明的别名使用子查询

SELECT day,TotalProfit, TotalRevenue, TotalProfit/TotalRevenue AS ProfitMargin
from (
SELECT 

        day,
        SUM(profit) AS TotalProfit,
        SUM(revenue) AS TotalRevenue
    FROM table
GROUP BY day
) as subq

当然我同意其他人看起来很开销

Answer 4

SELECT *,TotalProfit/TotalRevenue AS ProfitMargin from
 (select
    day,
    SUM(profit) AS TotalProfit,
    SUM(revenue) AS TotalRevenue       
FROM table) x
where

Answer 5

您需要使用子查询。然后，您可以使用data.TotalProfit / data.TotalRevenue AS ProfitMargin

SELECT 
   data.day
 , data.TotalProfit
 , data.TotalRevenue
 , (data.TotalProfit / data.TotalRevenue) AS ProfitMargin
FROM (
  SELECT
      day    
    , SUM(profit) AS TotalProfit
    , SUM(revenue) AS TotalRevenue
  FROM 
   table
)
 data

Answer 6

我最喜欢的方法是横向连接。这看起来像：

SELECT . . . ,
       v.exp1, v.exp2, v.exp1 / v.exp2
FROM table t, LATERAL
     (VALUES (<expression1>, <expression2>) ) v(exp1, exp2);

但是，要将此与聚合查询一起使用，无论如何都需要子查询。如果您使用子查询，只需将计算放在外部查询中。

如何重用两个计算列

6 个答案: