mscorlib.dll中发生了'System.InvalidCastException'类型的第一次机会异常

Question

我在rng = .Range.Copy From Recordset行上运行以下代码时收到错误消息.错误是"mscorlib.dll中出现'System.InvalidCastException'类型的第一次机会异常".我知道它不是输出,因为被注释掉的代码工作正常但速度很慢.我正在努力加快这个速度.这是代码

    Private Sub ButRun_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ButRun.Click
    Dim DWPROD As String = "Data Source=DWPROD;User ID=gayloj01;password=jgay0421;"
    Dim Conn As New Oracle.DataAccess.Client.OracleConnection
    Dim cmd As New Oracle.DataAccess.Client.OracleCommand
    Dim ds As New DataSet
    Dim dtAdapter As New Oracle.DataAccess.Client.OracleDataAdapter
    Dim Excel As Microsoft.Office.Interop.Excel.Application
    Dim rng As Microsoft.Office.Interop.Excel.Range

    SQLBuilder()
    Conn.ConnectionString = DWPROD
    With cmd
        .Connection = Conn
        .CommandText = strSQL
        .CommandType = CommandType.Text
    End With
    dtAdapter.SelectCommand = cmd
    ds.Tables.Add("RawData")
    dtAdapter.Fill(ds, "RawData")
    Try
        Excel = CType(GetObject(, "Excel.Application"), Microsoft.Office.Interop.Excel.Application)
    Catch ex As Exception
        Excel = New Microsoft.Office.Interop.Excel.Application
    End Try
    Try
        With Excel
            .SheetsInNewWorkbook = 1
            .Workbooks.Add()
            .Worksheets(1).Select()
            .Visible = True
            .ScreenUpdating = False
            rng = .Range(.Cells(1, 1), .Cells(ds.Tables("RawData").Rows.Count, ds.Tables("RawData").Columns.Count))
            rng.CopyFromRecordset(ds.Tables("RawData"), ds.Tables("RawData").Rows.Count, ds.Tables("RawData").Columns.Count)
            'Dim i As Integer = 1
            'For col = 0 To ds.Tables("RawData").Columns.Count - 1
            '.Cells(1, i).value = ds.Tables("RawData").Columns(col).ColumnName
            '.Cells(1, i).EntireRow.Font.Bold = True
            'i += 1
            'Next
            'i = 2
            'Dim j As Integer = 1
            'For col = 0 To ds.Tables("RawData").Columns.Count - 1
            'i = 2
            'For row = 0 To ds.Tables("RawData").Rows.Count - 1
            '.Cells(i, j).Value = ds.Tables("RawData").Rows(row).ItemArray(col)
            'i += 1
            'Next
            'j += 1
            'Next
            .ScreenUpdating = True
        End With
    Catch ex As Exception
        Debug.Print(ex.Message)
    End Try

End Sub

我认为这与我如何填补范围有关,但我无法解决任何问题.我是VB.net的新手,非常感谢能提供的任何帮助.

TIA

吉姆G.

Answer 1

在调试时会发生第一次机会异常,这是.NET Framework为调试器(即Visual Studio)提供处理问题的机会的方式.如果调试器无法解决第一次机会异常,那么它将成为您的代码应该处理的异常.如果您的代码没有处理异常,那么最终.NET Framework将处理它(即ASP.NET中的黄色死机屏幕).

您可以忽略第一次机会异常,因为它们是用于调试器的.换句话说,您的异常代码(try-catch逻辑)将不允许您与第一次机会异常进行交互.