Mysql 键不能为null-VB.net错误

我需要你们的帮助，伙计们。我有个错误。请参阅下面我的代码：

      Imports MySql.Data.MySqlClient
Public Class frmlogin
Dim conn As MySqlConnection = New MySqlConnection
Dim serverstring As String = "Server=localhost;User Id=root;Password=root;Database=dasystem"
Dim login As Boolean
Dim ds As DataSet
Dim cusds As DataSet
Dim da As MySqlDataAdapter
Dim dt As DataTable
Dim ctrshowlogin, ctrshowsearch As Integer


Private Sub btnlogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnlogin.Click
    Dim rowctr As Integer
    Dim password As String
    ctrshowlogin = 0
    ds = New DataSet
    da = New MySqlDataAdapter("select * from password", conn)
    da.Fill(ds, "pword")

    If cmbuser.SelectedItem = "Administrator" Then
        For rowctr = 0 To ds.Tables(0).Rows.Count - 1
            password = ds.Tables(0).Rows(rowctr).Item(0).ToString
            If password = txtpass.Text Then
                login = True
            End If
        Next (rowctr)
        If login = True Then
            MessageBox.Show("Login Successful!")
            frmcomodities.Show()
            Me.Hide()
            cmbuser.Text = ""
        ElseIf login = False Then
            MessageBox.Show("Wrong Password, Please try again.")
            txtpass.Focus()
        End If
    End If
End Sub

Private Sub Cancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)  Handles Cancel.Click
    Close()
End Sub
End Class

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有什么想法吗？我被这个问题困住了。如果你能帮忙，我将非常感激。谢谢。

您需要更改

da.Fill（ds，“pword”）

行中的表名，以匹配数据库表名（密码）：

或者干脆完全删除该参数

da.Fill(ds)

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错误发生在哪里？在这一行中：da.Fill（ds，“pword”）您真的有一个名为“Password”的表吗？它的模式是什么？

da.Fill(ds)