处理“列不属于表".例外 [英] Handling "Column does not belong to table" Exception

问题描述

If System.IO.File.Exists(strPathName & "_Master.xml") Then
            dsMaster.ReadXml(strPathName & "_Master.xml")
        Else
            MessageBox.Show("Master does not exist")

        End If
            Dim rowMaster() As DataRow = dsMaster.Tables(0).Select("FinYearID=" & GlobalClass.finYearId & " And MemType='" & GlobalClass.MemType & "' And MemberID='" & rowTran("MemberID") & "'")

Dim strBuilder As New StringBuilder
            strBuilder.AppendLine("<?xml version='1.0' encoding='utf-8'?>")
            'declare the start root.
            strBuilder.AppendLine("<ReportInfo>")
            strBuilder.Append("<Info>")

 strBuilder.Append("<Email>")
            Try
                strBuilder.Append(rowMaster(0)("Email") & "") ' to test if there is any "Email" column in master table or not ?
            Catch ex As Exception
                strBuilder.Append("")
            End Try
            strBuilder.Append("</Email>")

  strBuilder.Append("</Info>")
            'declare the end root.
            strBuilder.AppendLine("</ReportInfo>")

-------------------------------------------------- ----------------------------
我正在使用上面的代码来制作一个xml文件.
我正在从名为"master"的xml文件中读取数据.
在主文件中，缺少一些标签，例如<电子邮件>标签，因此当我阅读电子邮件标签时，它给我列不属于表"异常.

我可以使用try-catch块来处理此异常，但是我想知道是否可以通过if-else语句来处理该异常，例如"isDBNull"或"is No Nothing".

请告诉我是否有人知道...
我将非常感谢他/她.

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I am using the above code to make an xml file.
I am reading the data from an xml file named "master".
In master file there is some tag missing e.g. <email> tag, so when I read email tag it gives me "Column does not belong to table" Exception.

I can handle this exception with try-catch block, but I want to know if there is any way to handle it with if-else statement, like ''isDBNull'' or ''is Not Nothing''.

Please tell me if anyone knows...
I will be very thankful to him/her.

推荐答案

您可以像这样检查它

You can check it like that

if(dt.Columns.Contains("COLUMNNAME"))
   return dt.Rows(0)("COLUMNNAME") 
else
   return string.Empty

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