如何计算Storeprocedure中的列？

本文介绍了如何计算Storeprocedure中的列？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有以下商店程序，

i have store procedure following,

SELECT DISTINCT C.cid , C.custclientid , C.client , Cpany , C.product , C.producttakendate , C.total , P.reciveamt , P.dueamt , ( SELECT TOP 1 rcvdate FROM paymentdata AS PD1 WHERE PD1.pclientid=PD.pclientid AND PD1.productname=PD.productname ORDER BY rcvdate DESC) AS rcvdate , ( SELECT TOP 1 nxtdate FROM paymentdata AS PD1 WHERE PD1.pclientid=PD.pclientid AND PD1.productname=PD.productname ORDER BY rcvdate DESC) AS nxtdate , ( SELECT TOP 1 notepayment FROM paymentdata AS PD1 WHERE PD1.pclientid=PD.pclientid AND PD1.productname=PD.productname ORDER BY rcvdate DESC) AS notepayment FROM customermaintenance C LEFT OUTER JOIN payment P ON C.custclientid = P.pclientid LEFT OUTER JOIN paymentdata PD ON P.pclientid = PD.pclientid where C.custclientid=1 and C.product='Software'

c.total有5000 p.reciveamt有NULL p.dueamt有NULL i有datalist，有什么需要

c.total have 5000 p.reciveamt have NULL p.dueamt have NULL i have datalist, whic have

<asp:Label ID="nextamountLabel" runat="server" Text='<%# Eval("dueamt") %>' />

i想要输出dueamt = 5000然后我在这个程序中如何计算？

i want to out put dueamt=5000 then how i calculate in this procedure?

推荐答案

该标准规定任何涉及NULL的操作都将产生NULL。由于NULL不为零 - 它是不可用数据。因此，如果您故意在特殊情况下将NULL视为零，则必须手动执行。最简单的方法是使用 COALESCE（表达式，0）。 在你的情况下它会像这样一样： The standard states that any operation involving NULL will yield NULL. As NULL is not zero - it is unavailable data. So if you deliberatelly want to treat NULL as zero in a special case, you have to do it manually. The simplest approach is using COALESCE(expression, 0). In your case it will looke like this one: COALESCE(c.total,0)-COALESCE(p.reciveamt,0)