Interface我正在尝试将数据库中的数据显示到DataGridView，我成功地做到了这一点，但我希望以两种方式显示：1）显示所有记录和2）显示指定的记录。我可以使用两个组合框显示指定的记录：品牌和尺寸，通过从下拉列表中指定，数据显示在DataGridView上。但我现在想从下拉列表中显示所有品牌和所有尺寸，但它没有显示;它只显示两个查询中的一个。如何根据下拉列表的选择来显示代码？
我放置了一个if语句，检查用户是否选择了ComboBox1：所有轮胎和组合框2：所有轮胎，那么它应该执行所有查询。如果没有，用户只选择了一种类型的品牌和大小，那么它将显示只是与另一个查询。
接口：这是密码：

Private Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
    MysqlConn = New MySqlConnection
    MysqlConn.ConnectionString = "server=localhost;userid=root;password=root;database=golden_star"

    ''connecting data grid with the database
    Dim Sda As New MySqlDataAdapter
    Dim dbdataset As New DataTable
    Dim bSource As New BindingSource

    Try
        MysqlConn.Open()
        Dim Query As String
        Dim All As String

        If ComboBox1.Text = "ALL TYRES" & ComboBox2.Text = "ALL SIZES" Then
            All = "select * from golden_star.sales"
            Command = New MySqlCommand(All, MysqlConn)

        End If

       Query = "select sale_id,date,brand,size,selling_unit_price,cost_unit_price,quantity,cost_of_goods,profit,total_cost_price from golden_star.sales where brand = '" + ComboBox1.Text + "' and size = '" + ComboBox2.Text + "' "

        Command = New MySqlCommand(Query, MysqlConn)





        Sda.SelectCommand = Command
        Sda.Fill(dbdataset)
        bSource.DataSource = dbdataset
        DataGridView1.DataSource = bSource
        Sda.Update(dbdataset)

        MysqlConn.Close()
    Catch ex As MySqlException
        MessageBox.Show(ex.Message)

    Finally
        MysqlConn.Dispose()
    End Try

End Sub