为什么不比较工作

Question

这是一个登录代码，它还假设验证此人是“管理员”还是“工作人员”。

Private Sub btnopenapplication_Click(sender As System.Object, e As System.EventArgs) Handles btnlogin.Click

    Dim reader As SqlDataReader

    Dim verify_account_type As String

    Dim sqlstatement As SqlCommand = New SqlCommand
    sqlstatement.Connection = connection

    Try
        sqlstatement.CommandText = "Select account_username, account_password, account_type " &
    "from login_account where account_username='" & txtusername.Text & "' and account_password='" & txtpassword.Text & "'"

        reader = sqlstatement.ExecuteReader()

        If (reader.Read()) Then
            Dim account_type As String = "Administrator"
            verify_account_type = CStr(reader("account_type").ToString)

            If String.Compare(account_type, verify_account_type) = 0 Then

                application_form.Show()
                Me.Visible = False

            Else
                MsgBox("you are not an administrator")
            End If

            sqlstatement.Dispose()
            reader.Close()

        Else
            MsgBox("Invalid")
        End If
            reader.Close()
    Catch ex As Exception
        MsgBox(vbCrLf & ex.Message)
    End Try

End Sub

这是它似乎失败的地方

            If String.Compare(account_type, verify_account_type) = 0 Then

                application_form.Show()
                Me.Visible = False

            Else
                MsgBox("you are not an administrator")
            End If

登录有效，但无法进行比较。基本上我有一个帐户类型的数据库（“管理员”和“工作人员”）。它假设读取account_type并将值放入一个变量，在该变量中，该变量将其与另一个值为“Administrator”或“Staff”的变量进行比较，但事实并非如此。

一些帮助将不胜感激，谢谢。