在查询中稍后使用'AS ColumnName'的值

Question

我正在制作一个存储过程,我需要使用之前设置的值.我很难解释这个,所以我将使用一个例子:

  CASE 
     WHEN ((select top 1 stuksweergeven from componenten
            where componentid = componentlink.componentid) = 1) and
          ((select opbrengstperkilo from componenten
            where componentid = componentlink.componentid) <> 0) THEN 
        amount1 * (select opbrengstperkilo from componenten
                   where componentid = componentlink.componentid)
     ELSE 
        amount1
  END AS Total,
Amount1 * Total *(SELECT dbo.SelectReceptenLinkGewicht(Componentid,0)) AS TotalWeight

我做了一个CASE给它结果为Total.之后我想使用Total来计算TotalWeight.

对不起我的英语不好.

Answer 1

问题是SELECT列表中的所有表达式都是以all at once方式进行评估的.这就是你需要复制代码的原因.但你可以subquery为此创造或cte喜欢:

with cte as(
             select Amount1,
                    ComponentID,
                    CASE 
                       WHEN ((select top 1 stuksweergeven from componenten where componentid = componentlink.componentid) = 1) and  ((select opbrengstperkilo from componenten where componentid = componentlink.componentid) <> 0) 
                       THEN amount1 * (select opbrengstperkilo from componenten where componentid = componentlink.componentid)
                       ELSE amount1
                    END AS Total
             from SomeTable)

select Total,
       Amount1 * Total *(SELECT dbo.SelectReceptenLinkGewicht(Componentid,0)) AS TotalWeight
from cte

要么:

select Total,
       Amount1 * Total *(SELECT dbo.SelectReceptenLinkGewicht(Componentid,0)) AS TotalWeight
from (
             select Amount1,
                    ComponentID,
                    CASE 
                       WHEN ((select top 1 stuksweergeven from componenten where componentid = componentlink.componentid) = 1) and  ((select opbrengstperkilo from componenten where componentid = componentlink.componentid) <> 0) 
                       THEN amount1 * (select opbrengstperkilo from componenten where componentid = componentlink.componentid)
                       ELSE amount1
                    END AS Total
             from SomeTable) t