与MySql的图表连接

我正在连接mysql数据库中的图表对象，但出现以下错误：

对象引用未设置为对象的实例

这是我使用的代码：

Imports MySql.Data.MySqlClient
Public Class Form1
    Dim con As New MySqlConnection
    Dim com As MySqlCommand
    Dim dt As New DataTable

    Private Sub btnlaod_Click(sender As Object, e As EventArgs) Handles btnlaod.Click
        con = New MySqlConnection
        con.ConnectionString = "server=localhost;userid=root;password=;database=noh_mis"
        Dim Reader As MySqlDataReader

        Try
            con.Open()
            Dim query As String
            query = "Select * From database.students_profile"
            Reader = com.ExecuteReader
            While Reader.Read
                Chart1.Series("Male").Points.AddXY(Reader.GetString("Gender"), Reader.GetString("GradeLevel"))
            End While
            con.Close()
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            con.Dispose()
        End Try

    End Sub

End Class

---

在使用

com.ExecuteReader

之前，不能发出命令。您创建了一个sql字符串，但从未将其连接到数据库

尝试在生成

query

之后，但在

Reader=com.ExecuteReader

之前添加以下行：

com = New MySqlCommand(query, con)