Vb.net女士訪問 - 沒有給出一個或多個所需參數的值

我的下面的代碼有什麼問題。它始終顯示一個錯誤：沒有給出一個或多個必需參數的值。感謝幫助。Vb.net女士訪問 - 沒有給出一個或多個所需參數的值

 Dbcon.Open() 

     Dim query As String 
     Dim dbup As New OleDbCommand 

     For x As Integer = 0 To IncomingMailDGV.Rows.Count - 1 
      Dim received As String = IncomingMailDGV.Rows(x).Cells(0).Value 
      Dim subject As String = IncomingMailDGV.Rows(x).Cells(1).Value 
      Dim contents As String = IncomingMailDGV.Rows(x).Cells(2).Value 

      query = "SELECT ReceivedDateTime, Subject, MessageContents FROM IncomingAlerts WHERE ReceivedDateTime = @ReceivedDateTime AND MessageContents [email protected]" 
      dbup = New OleDbCommand(query, Dbcon) 
      dbup.Parameters.AddWithValue("ReceivedDateTime", received) 
      dbup.Parameters.AddWithValue("MessageContents", contents) 
      Dim readinputs As OleDbDataReader 
      readinputs = dbup.ExecuteReader() 

      If readinputs.HasRows = False Then 

       Dim InsertData As String 
       InsertData = "INSERT INTO IncomingAlerts(ReceivedDateTime, Subject, MessageContents) Values (@ReceivedDateTime, @Subject, @MessageContents)" 
       dbup.Parameters.AddWithValue("ReceivedDateTime", received) 
       dbup.Parameters.AddWithValue("Subject", subject) 
       dbup.Parameters.AddWithValue("MessageContents", contents) 
       dbup = New OleDbCommand(InsertData) 

       With dbup 
        .CommandText = InsertData 
        .Connection = Dbcon 
        .ExecuteNonQuery() 
       End With 
      End If 
     Next

更新：

進出口使用vb.net - datagridview的和MSACCESS。

來源

2015-07-19 phil_19

是否有可能收到，主題或內容是什麼？ – Saragis

不可能。所有都有價值。 –

你的問題是在這一段代碼：

  dbup.Parameters.AddWithValue("ReceivedDateTime", received) 
      dbup.Parameters.AddWithValue("Subject", subject) 
      dbup.Parameters.AddWithValue("MessageContents", contents) 
      dbup = New OleDbCommand(InsertData)

你加入所有需要的參數，然後初始化一個新的命令對象，它有效地清除所有加入預先參數。在創建命令後添加參數應該解決這個問題。

來源

2015-07-19 18:36:42 Saragis

它現在正在工作。謝謝！ –

Vb.net女士訪問 - 沒有給出一個或多個所需參數的值

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