是否有任何可能的方式來執行此操作而不會出現此錯誤「已經有一個與此連接關聯的打開的DataReader,必須先關閉該連接。」我已經嘗試使用「dr.close()
」,並且我收到另一個錯誤,指出「讀取器關閉時讀取無效嘗試」。你能幫我嗎?如何在打開閱讀器的情況下在VB中打開execuete查詢?
繼承人我的代碼:
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Label2.Text = AllPicker1.Text
Label3.Text = AllPicker2.Text
If AllPicker1.Value >= AllPicker2.Value Then
MsgBox("End Date Must be Greater!")
Else
Dim SQLstatement As String = "SELECT * FROM tblStudInfo,tbl_studentLog WHERE tblStudInfo.StudID = tbl_studentLog.StudentNumber AND tbl_studentLog.LoginDate BETWEEN '" & AllPicker1.Text & "' AND '" & AllPicker2.Text & "'"
OpenData(SQLstatement)
End If
End Sub
Public Sub OpenData(ByRef SQLstatement As String)
Dim cmd As MySqlCommand = New MySqlCommand
With cmd
.CommandText = SQLstatement
.CommandType = CommandType.Text
.Connection = SqlConnection
dr = .ExecuteReader()
End With
While dr.Read
Dim SQLstatementSave As String = "INSERT INTO tbl_report (RepStudNo,RepName,RepCourse,RepDept,RepLogTime,RepLogdate) VALUES ('" & dr("StudID") & "','" & dr("Name") & "','" & dr("Course") & "','" & dr("Dept") & "','" & dr("LoginTime") & "','" & dr("LoginDate") & "') "
dr.Close()
Save(SQLstatementSave)
End While
SqlConnection.Close()
SqlConnection.Dispose()
SqlConnection.Open()
End Sub
Public Sub Save(ByRef SQLstatementSave As String)
Dim cmd As MySqlCommand = New MySqlCommand
With cmd
.CommandText = SQLstatementSave
.CommandType = CommandType.Text
.Connection = SqlConnection
.ExecuteNonQuery()
End With
SqlConnection.Close()
SqlConnection.Dispose()
SqlConnection.Open()
End Sub
End Class
像這樣構建查詢的字符串連接會讓您容易受到sql注入攻擊。這真是太糟了。** –