如何给ADOQuery添加一个不存在的字段

[VeryOldMan]

我有一表，结构如下：
Table1(Name, Year, Month, Float1, Float2)
我用了以下SQL语句输出结果：
Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2
From Table1 Group By Name, Year, Month Order By Name, Year DESC
我现在需要在数据中增加一个新字段：F3，其值为F2/F1。

我试过以下代码，但无论放在什么事件中均通不过：
var
NewField : TField;
begin
NewField := TField.Create(Self);
NewField.FieldName := 'F3';
NewField.SetFieldType := ftFloat;
NewField.DataSet := ADOQuery1;
ADOQuery1.Fields.Add(NewField);
end;

有什么方法可以解决此问题？

[VeryOldMan]

to: hnhb(不死鸟)
谢谢。我也用过您所示代码，但运行时显示语法错误，在“>”处。

menggirl(看天上浮云，胜似闲庭信步) ：
我现在用的就是您给出的代码，但我相信当F1为0时，肯定有问题。

先谢谢两位。

[hnhb]

你是什么数据库啊？？
其实我刚才写得也有些错误，只需判断sum(Float2)<>0就行了

[VeryOldMan]

to : hnhb(不死鸟)

MS SQL 2000。
就是死活不让过，比我顽固多了！！ :)
谢谢。

[maycy]

关注

[maycy]

oncalcfields

[hnhb]

Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2,case sum(Float2)>0 then sum(Float1)/sum(Float2) as yourNewField end
From Table1 Group By Name, Year, Month Order By Name, Year DESC

[menggirl]

Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2
SUM(Float1) /SUM(Float2) as F3
From Table1 Group By Name, Year, Month Order By Name, Year DESC

[chenar]

Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2
(case when SUM(Float2)<>0 then SUM(Float1) /SUM(Float2) else 0 end) as F3
From Table1 Group By Name, Year, Month Order By Name, Year DESC

[maimaizhi]

Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2,,CONVERT(Float,SUM(Float2)/SUM(Float1)) From Table1 Group By Name, Year, Month Order By Name, Year DESC

[maimaizhi]

错了,应是这样
CONVERT(Float,F3)=SUM(Float2)/SUM(Float1))

[VeryOldMan]

问题已解决，多谢各位！

其实本问题有两种方法：
1、如同在客户端为记录添加序号列一样，添加一个计算字段，也应该能解决问题。
2、采用SQL语句实现，就如上面几位所述。

当然，采用2最简单。

maimaizhi(mutiny)兄弟：
你的那一句应该为：
Select Name, Year, Month, SUM(Float1) AS F1, SUM(Float2) AS F2, CONVERT(Float, SUM(Float2)/SUM(Float1)) AS F3 From Table1 Group By Name, Year, Month Order By Name, Year DESC

chenar(梧桐_WQ)兄弟：
我恨得你直咬牙——你把我的真名作为你的昵称！！ : )

结帖啦！谢谢各位！

[chenar]

我不是故意的 :_(