Question

我正在从Excel VBA过渡到VB.NET，所以如果这是一个愚蠢的问题，请放轻松我。我在以下子行的这一行得到NullReferenceException was unhandled by user code：

Dim objSheet As Excel.Worksheet = objBook.Sheets("SQL Creator")

VS说Object reference is not set to an instance of the object。我不确定为什么要这样做，因为我已经在objApp变量中声明了一个新的Excel实例。为什么我需要在该类下声明每个对象的新实例？我很可能没有正确地思考这个问题，但我只是想提一下我的想法。总的来说，我只是试图测试下面的子项，看看它是否会打开和关闭与PostgreSQL数据库的连接。

导入Microsoft.Office.Interop

    Public Sub QueryData(ByVal ribbonUI As Office.IRibbonControl)

            Dim objApp As New Excel.Application
            Dim objBook As Excel.Workbook = objApp.ActiveWorkbook
            Dim objSheet As Excel.Worksheet = objBook.Sheets("SQL Creator")
            Dim pgconn As String

            pgconn = "Driver={PostgreSQL};" &
            "Server = localhost;" &
            "Port = 5432;" &
            "Database = CFABudget;" &
            "Uid = postgres;" &
            "Pwd = budgeto;"

            Dim SQL As String = objSheet.Range("BudgetSQL").Text
            Dim conn As New Data.Odbc.OdbcConnection(pgconn)
            Dim cmd As Data.Odbc.OdbcCommand = New Data.Odbc.OdbcCommand(SQL)

            conn.Open()

            MsgBox("Success!", vbOKOnly)

            conn.Close()


        End Sub

谢谢大家的帮助！

Answer 1

替换

Dim objApp As New Excel.Application

使用：

Dim objApp As Excel.Application = System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application")

您试图从新的空Excel实例中获取活动工作簿。

NullReferenceException未被用户代码处理 - 声明Excel.Worksheet对象

1 个答案: