mysql - 如何解决 "No query in datareader"错误？

Question

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:

No current query in datareader.

问题出在哪里以及如何解决？

Answer 1

您可能在这里缺少 With 语句，例如 dr1.Read() 行后面的 With dr1...但我只需像这样更改它:

将 id 调暗为 Integer = dr1(0)
将用户名变暗为字符串 = dr1(1)