how to bind data from database to dropdownlist on another dropdownlist's selected index change?

This is a solution which assumes that you load all data at once, which will work fine as long as there aren't too many items - which there shouldn't be because otherwise it wouldn't be useful to let the user select with ComboBoxes.

It works by setting the RowFilter-Property of the DataView that is the DataSource for the "child"-ComboBox when you select a new entry of the "parent"-ComboBox.

Somewhere in your Form-startup (in the constructor or OnLoad(..)- or OnShown(..)-overrides):

brandComboBox.DataSource = brandTbl.DefaultView;
brandComboBox.ValueMember = "id";
brandComboBox.DisplayMember = "brandName";

typeComboBox.DataSource = typeTbl.DefaultView;
typeComboBox.ValueMember = "id";
typeComboBox.DisplayMember = "type";

BrandComboBoxSelectedIndexChanged(null, null);
brandComboBox.SelectedIndexChanged += BrandComboBoxSelectedIndexChanged;

As a method in your form:

private void BrandComboBoxSelectedIndexChanged(object sender, EventArgs e)
{
    if (brandComboBox.ValueMember == "id")
        ((DataView)typeComboBox.DataSource).RowFilter = "brandId = " + brandComboBox.SelectedValue;
}