VB.NET 求助：数据库查询取不到数据

Imports MySql.Data.MySqlClient

Public Class Form1

    '数据连接对象

    Dim con As New MySqlConnection

    Dim comm As New MySqlCommand



    '登录数据

    Dim user As String

    Dim pas As String

    REM 登录功能

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        '提取输入条件

        user = Username.Text

        pas = Password.Text

        Debug.Print(user + Chr(10) + pas)

        '查询语句

        Dim sql As String = "select * from userinfo where userName = '" & user & "'"

        Debug.Print(sql)

        comm = New MySqlCommand(sql, con)

        Dim da = New MySqlDataAdapter(sql, con)

        Dim dt = New DataSet()

        da.Fill(dt, "sql")

        MsgBox(dt.Tables("sql").Rows.Count)

        con.Close()





    End Sub

    '取消功能

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

        Username.Text = ""

        Password.Text = ""

    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        '数据连接

        con.ConnectionString = "Server=127.0.0.1;UserID=root;Password=12345;Database=candy"

        con.Open()

        '数据连接状态判别

        If con.State = ConnectionState.Open Then

            Debug.Print("数据库连接成功！")

        Else

            Debug.Print("数据库连接失败！")

        End If

    End Sub



End Class