“索引0是负数或在行数以上”。错误C＃ [英] "Index 0 is either negative or above row count" error C#

问题描述

我需要太多帮助。

我收到以下异常：

索引0为负或上面的行计数错误

Index 0 is either negative or above row count error

我在stackoverflow和google中进行了研究，但无法修复错误。

I researched in stackoverflow and google, but I couldn't fixed error.

我的代码：

if (lb_Gmy.SelectedItems.Count > 0)
{
    string gmyquery = "Select * from tblA (nolock) where ParameterID = 2 and Status = 1";
    DataView dataw = new DataView(ReturnTable(gmyquery));

    foreach (string item in lb_Gmy.SelectedItems)
    {
        dataw.RowFilter = "Value = '" + item + "'";
        gmy += dataw[0]["ParamValue"].ToString() + ",";
    }

    gmy = gmy.Substring(0, gmy.Length - 1);
}

但是此代码中没有出现错误：

But I am not getting an error in this code:

if (lb_Fg.SelectedItems.Count > 0)
{
    string gmyquery = "Select * from tblA (nolock) where ParameterID = 2 and Status = 1";
    DataView dataw = new DataView(ReturnTable(gmyquery));

    foreach (string item in lb_Fg.SelectedItems)
    {
        dataw.RowFilter = "Value = '" + item + "'";
        findingGmy += dataw[0]["ParamValue"].ToString() + ",";
    }

    findingGmy = findingGmy.Substring(0, findingGmy.Length - 1);
}

它们看起来一样。我很困惑。问题出在哪里？请告诉我。

They are looking same. I'm confused so much. Where is the problem? Tell me please.

推荐答案

这表示DataView， dataw 为空（查询不返回任何记录）。因此，您必须先检查是否为空，然后才能从中访问值。

Which means the DataView, dataw is Empty(the query returns no records) . So you have to Check for Empty before accessing the Value from it.

DataView dataw = new DataView(ReturnTable(gmyquery));
if (dataw!=null && dataw.Count > 0)
{
    // Your code here
}

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