如何解决“数据读取器中没有查询”错误？

考虑以下代码：

 answer = today.AddDays(356)
 Dim command1 As New MySqlCommand("Insert into UserScanner (Username,Password,Address,Contact,SubStart,SubEnd,Active) VALUES('" & txtbox_username.Text.Trim & "','" & txtbox_password.Text & "','" & txtbox_add.Text & "','" & txtbox_contact.Text & "','" & today.ToString & "','" & answer.ToString & "',1)", Connection)
 command1.ExecuteNonQuery()
 MsgBox("Profile Successfuly Saved")
 Dim command2 As New MySqlCommand("Select * From userscanner WHERE Username = '" & txtbox_username.Text & "' ", Connection)
 command2.ExecuteNonQuery()
 Dim dr1 As MySqlDataReader
 dr1 = command2.ExecuteReader
 dr1.Read()
 Dim id As Integer = .Item(0)
 Dim Username As String = .Item(1)
 Dim command3 As New MySqlCommand("Insert into Trasnsaction (ID,Username,Description,Date) VALUES('" & id & "','" & Username & "','Register Account','" & today & "')", Connection)
 command3.ExecuteNonQuery()
 dr1.Close()
 Me.Close()
 frm_main.Show()

让我们重点关注这些行：

 Dim command2 As New MySqlCommand("Select * From userscanner WHERE Username = '" & txtbox_username.Text & "' ", Connection)
 command2.ExecuteNonQuery()
 Dim dr1 As MySqlDataReader
 dr1 = command2.ExecuteReader

上面的代码产生一个错误，指出：

数据读取器中没有当前查询。

问题出在哪里以及如何解决？

您可能缺少一个With在这里声明，比如With dr1就在之后dr1.Read()线...但我会这样改变它：

Dim id as Integer = dr1(0)
Dim Username As String = dr1(1)