DataReader的仍然是開放的，由於我的查詢

Question

我有這樣的錯誤有關DataReader仍處於打開狀態，但我發現，如果我使用一個不同的查詢/命令它工作正常

所以這個問題是我mycommand的字符串，但這是我需要加載所需的數據，所以任何建議如何解決它？由於

 Private Sub daily() 
    Cursor = Cursors.WaitCursor() 
     MySQLcon.ConnectionString = MySQLserver 
     MySQLcon.Open() 
     'strPath & "\" & txtName.Text & ".xlsx" 
     Dim dte As String = cboDate1.Text 
     Dim myCommand1 As New MySql.Data.MySqlClient.MySqlCommand 
     Dim myadapter As New MySql.Data.MySqlClient.MySqlDataAdapter 
     Dim mybuilder As New MySql.Data.MySqlClient.MySqlCommandBuilder 
     Dim mydatatable As New DataTable 
     Dim mydataset As New DataSet 
     myCommand1.Connection = MySQLcon 

     'myCommand1.CommandText = "SELECT `" + dte + "`.`Users`,concat((`users`.`Last Name`),', ',(`users`.`First Name`)) as `Name`,'" + dte + "' as Date,`" + dte + "`.`Activity`,`" + dte + "`.`Field1` as `Project Name`,`" + dte + "`.`Field2` as `Job Name` ," + _ 
     ' "SUM(`" + dte + "`.`Field4`) as `Records`, SUM(`" + dte + "`.`Field5`)as Pages," + _ 
     ' "ROUND(sum(TIME_TO_SEC(`" + dte + "`.`Elapsed Time`))/3600,2)as `Hours`," + _ 
     ' "'G' as `REGS/HR`," + _ 
     ' "'H' as `PGS/HR`" + _ 
     ' "FROM `" + dte + "`" + _ 
     ' "INNER JOIN `users`" + _ 
     ' "ON `" + dte + "`.`Users`=`users`.`Employee ID`" + _ 
     ' "Where `" + dte + "`.`Group` = 'DATA ENTRY' and `" + dte + "`.`Field1` <> 'OVER-BREAK 1' and `" + dte + "`.`Field1` <> 'OVER-BREAK 2' and (`" + dte + "`.`Activity` = 'KE' or `" + dte + "`.`Activity` = 'CH' or `" + dte + "`.`Activity` = 'SJ' or `" + dte + "`.`Activity` = 'VE' or `" + dte + "`.`Activity` = 'MB' or `" + dte + "`.`Activity` = 'TD' or `" + dte + "`.`Activity` = 'LK' or `" + dte + "`.`Activity` = 'PG')" + _ 
     ' "GROUP BY `" + dte + "`.`Users`, `" + dte + "`.`Activity`, `" + dte + "`.`Field1`" 

     myCommand1.CommandText = "SELECT `MERGED DATAENTRY`.`Users`,concat((`users`.`Last Name`),', ',(`users`.`First Name`)) as `Name`,'" + cboDate1.Text & " - " & cboDate2.Text + "' as Date,`MERGED DATAENTRY`.`Activity`,`MERGED DATAENTRY`.`Field1` as `Project Name`,`MERGED DATAENTRY`.`Field2` as `Job Name` ," + _ 
      "SUM(`MERGED DATAENTRY`.`Field4`) as `Records`, SUM(`MERGED DATAENTRY`.`Field5`)as Pages," + _ 
      "ROUND(sum(TIME_TO_SEC(`MERGED DATAENTRY`.`Elapsed Time`))/3600,2)as `Hours`," + _ 
      "'G' as `REGS/HR`," + _ 
      "'H' as `PGS/HR`" + _ 
      "FROM `MERGED DATAENTRY`" + _ 
      "INNER JOIN `users`" + _ 
      "ON `MERGED DATAENTRY`.`Users`=`users`.`Employee ID`" + _ 
      "Where `MERGED DATAENTRY`.`Group` = 'DATA ENTRY' and `MERGED DATAENTRY`.`Field1` <> 'OVER-BREAK 1' and `MERGED DATAENTRY`.`Field1` <> 'OVER-BREAK 2' and (`MERGED DATAENTRY`.`Activity` = 'KE' or `MERGED DATAENTRY`.`Activity` = 'CH' or `MERGED DATAENTRY`.`Activity` = 'SJ' or `MERGED DATAENTRY`.`Activity` = 'VE' or `MERGED DATAENTRY`.`Activity` = 'MB' or `MERGED DATAENTRY`.`Activity` = 'TD' or `MERGED DATAENTRY`.`Activity` = 'LK' or `MERGED DATAENTRY`.`Activity` = 'PG')" + _ 
      "GROUP BY `MERGED DATAENTRY`.`Users`, `MERGED DATAENTRY`.`Activity`, `MERGED DATAENTRY`.`Field1`" 
     myadapter.SelectCommand = myCommand1 
     myadapter.Fill(mydataset) 
     mydataset.Tables.Add(mydatatable) 
     DataGridView1.DataSource = mydataset.Tables(0) 

     Dim xlApp As Microsoft.Office.Interop.Excel.Application 
     Dim xlWorkBook As Microsoft.Office.Interop.Excel.Workbook 
     Dim xlWorkSheet As Microsoft.Office.Interop.Excel.Worksheet 
     Dim misValue As Object = System.Reflection.Missing.Value 


     Dim i As Integer 
     Dim j As Integer 

     xlApp = New Microsoft.Office.Interop.Excel.ApplicationClass 
     xlWorkBook = xlApp.Workbooks.Add(misValue) 
     xlWorkSheet = xlWorkBook.Sheets("sheet1") 


     For i = 0 To DataGridView1.RowCount - 1 
      For j = 0 To DataGridView1.ColumnCount - 1 
       For k As Integer = 1 To DataGridView1.Columns.Count 
        'Dim style As Excel.Style = xlWorkSheet.Application.ActiveWorkbook.Styles.Add("NewStyle") 
        'style.Interior.Color = System.Drawing.ColorTranslator.ToOle(System.Drawing.Color.Yellow) 
        'xlWorkSheet.Cells(1, k).Style = "NewStyle" 
        xlWorkSheet.Cells(1, k) = DataGridView1.Columns(k - 1).HeaderText 
        xlWorkSheet.Cells(i + 2, j + 1) = DataGridView1(j, i).Value.ToString() 
        If DataGridView1(j, i).ColumnIndex = 9 Then 
         xlWorkSheet.Cells(i + 2, j + 1) = "=ROUND(" & DataGridView1(j, i).Value.ToString() & (DataGridView1(j, i).RowIndex + 2) & "/" & "I" & (DataGridView1(j, i).RowIndex + 2) & ",2)" 

        End If 
        If DataGridView1(j, i).ColumnIndex = 10 Then 
         xlWorkSheet.Cells(i + 2, j + 1) = "=ROUND(" & DataGridView1(j, i).Value.ToString() & (DataGridView1(j, i).RowIndex + 2) & "/" & "I" & (DataGridView1(j, i).RowIndex + 2) & ",2)" 

        End If 
       Next 
      Next 
     Next 

     xlWorkSheet.SaveAs(strPath & "\" & txtName.Text & ".xlsx") 
     xlWorkBook.Close() 
     xlApp.Quit() 
     ReleaseObject(xlApp) 
     ReleaseObject(xlWorkBook) 
     ReleaseObject(xlWorkSheet) 
     MessageBox.Show("File Export Successfully!") 
    MySQLcon.Close() 

End Sub 

Answer 1

MySQLDataAdapter用於IDisposable的，你是不是處置它 MySQLcon和MySQLserver你發佈的代碼之外定義的，所以我在這裏做一些假設。

我會想象有連接池在這裏，即你不真的每次你運行這個時得到一個新的數據庫連接。由於您在第二次或以後的時間點擊此代碼時不會丟棄MySqlDataAdapter等內容，因此您仍然需要使用數據庫打開「查詢」。

您需要檢查IDisposable接口上的所有的：

Dim myCommand1 As New MySql.Data.MySqlClient.MySqlCommand 
Dim myadapter As New MySql.Data.MySqlClient.MySqlDataAdapter 
Dim mybuilder As New MySql.Data.MySqlClient.MySqlCommandBuilder 
..... 

，並切換到使用statments，即：

Using myadapter As New MySql.Data.MySqlClient.MySqlDataAdapter 
    Using myCommand1 As New MySql.Data.MySqlClient.MySqlCommand 
     Using mybuilder As New MySql.Data.MySqlClient.MySqlCommandBuilder 
     ..... 
     End Using 
    End Using 
End Using 

雖然我懷疑DataAdaptor是唯一一個真正重要的。

嘗試在IDisposable接口讀了

NB mydataset.Tables.Add，要添加一個空白表到一個已經裝滿數據集（mydatatable）看起來毫無意義的